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Chng 1 S in li

A-r-ni-ut(*)

Mt loi my o pH c dng trongphng th nghim

Khi cc axit, baz v mui ho tan trong nc xy ra nhng hin tng

g v h qu ca qu trnh ho tan ny ra sao ?

Phn ng xy ra trong dung dch nc c nhng c im g ?

(*) (S. Arrhenius, 1859 1927), ngi Thu in, c gii Nobel v ho hc nm 1903.

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SIN LISIN LIBi 1

Bit cc khi nim v s in li vcht in li.Bit cc khi nim v s in li vcht in li.Hiu nguyn nhn tnh dn in ca dung dch cht in li v cch ca qu trnh in li.Hiu nguyn nhn tnh dn in ca dung dch cht in li v cch ca qu trnh in li.

I Hin tng in liI Hin tng in li

1. Th nghim1. Th nghim

Chun b ba cc : cc a ng nc ct, cc b ng dung dch saccaroz(ng knh trng tinh khit), cc c ng dung dch NaCl ri lp vo b dngc nhhnh 1.1.

Chun b ba cc : cc a ng nc ct, cc b ng dung dch saccaroz(ng knh trng tinh khit), cc c ng dung dch NaCl ri lp vo b dngc nhhnh 1.1.

Hnh 1.1. B dng c chng minh tnh dn in ca dung dch.Hnh 1.1. B dng c chng minh tnh dn in ca dung dch.

Khi ni cc u dy dn in vi ngun in, ta thy ch bng n cc ng

dung dch NaCl bt sng. Vy dung dch NaCl dn in, cn nc ct v dung

dch saccaroz khng dn in.

Khi ni cc u dy dn in vi ngun in, ta thy ch bng n cc ng

dung dch NaCl bt sng. Vy dung dch NaCl dn in, cn nc ct v dung

dch saccaroz khng dn in.

Nu lm cc th nghim tng t, ngi ta thy NaCl rn, khan, NaOH rn, khan,

cc dung dch ancol etylic, glixerol khng dn in. Ngc li cc dung dch axit,

baz v mui u dn in.

Nu lm cc th nghim tng t, ngi ta thy NaCl rn, khan, NaOH rn, khan,

cc dung dch ancol etylic, glixerol khng dn in. Ngc li cc dung dch axit,

baz v mui u dn in.

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2. Nguyn nhn tnh dn in ca cc dung dch axit, baz v muitrong nc

Ngay t nm 1887, A-r-ni-ut chng minh rng, tnh dn in ca cc dung

dch axit, baz v mui l do trong dung dch ca chng c cc tiu phn mang

in tch chuyn ng t do c gi l cc ion.

Nh vy cc axit, baz v mui khi ho tan trong nc in li ra cc ion, nn

dung dch ca chng dn in.

Qu trnh in li cc cht trong nc ra ion l s in li. Nhng cht tan

trong nc in li ra ion c gi l nhng cht in li.(*)

Vy axit, baz v mui l nhng cht in li.

II C ch ca qu trnh in li

1. Cu to ca phn t H2OPhn t H2O c cu to nh hnh 1.2. Lin kt O H l lin kt cng ho tr

phn cc, cp electron dng chung lch v pha oxi, nn oxi c d in tch m,

cn hiro c din tch dng. V vy, phn t H2O l phn t phn cc.

Hnh 1.2. a) Cu to ca phn t nc ; b) M hnh c ca phn t nc

2. Qu trnh in li ca NaCl trong nc

(*) Nhiu cht khi nng chy cng in li ra ion, nn trng thi nng chy cc cht ny dnin c. Trong mt s ti liu, ngi ta cng cp n cht in li loi ny, th d Al2O3.

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NaCl l

hp cht ion, ngha l

gm nhng cation Na

+

v

anion Cl

lin kt vinhau bng lc tnh in. Khi cho NaCl tinh th vo nc, nhng ion Na+ v Cl

trn b mt tinh th ht v chng cc phn t H2O (cation ht u m v anion

ht u dng). Qu trnh tng tc gia cc phn t nc phn cc v cc ionca mui kt hp vi s chuyn ng hn lon khng ngng ca cc phn t

nc lm cho cc ion Na+ v Cl

ca mui tch dn khi tinh th v ho tan

trong nc (hnh 1.3).

Hnh 1.3. S qu trnh in li ra ion ca tinh th NaCl trong nc.

T s trn ta thy s in li ca NaCl trong nc c th c biu din bng

phng trnh in li nhsau :

NaCl (dd) Na+ (dd) + Cl

(dd)

Tuy nhin, n gin ngi ta thng vit :

NaCl Na+ + Cl

3. Qu trnh in li ca HCl trong ncPhn t hiro clorua (HCl) cng l phn t phn cc tng t phn t nc.

Cc dng pha hiro, cc m pha clo.

Khi tan trong nc, cc phn t HCl ht v chng nhng cc ngc du ca cc

phn t nc. Do s tng tc gia cc phn t nc v phn t HCl, kt hp vi

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s chuyn ng khng ngng ca cc phn t nc dn n s in li phn t HCl

ra cc ion H+ v Cl

(hnh 1.4).

Hnh 1.4. S qu trnh in li ra ion ca phn t HCl trong nc.

Phng trnh in li ca HCl trong nc nhsau :

HCl H+ + Cl

Trong cc phn t ancol etylic, saccaroz, glixerol, c s phn cc nhng rtyu, nn di tc dng ca cc phn t nc chng khng th in li thnh ionc, chng l cc cht khng in li.

Bi tp

1. S in li, cht in li l g ? Nhng loi cht no l cht in li ? Ly mt s th d vcht in li v cht khng in li.

2. Theo thuyt in li, cc dung dch axit, baz v mui dn in c l do nguyn nhn g ?

3. Trong s cc cht sau, nhng cht no l cht in li ?

H2S, SO2, Cl2, H2SO3, CH4, NaHCO3, Ca(OH)2, HF, C6H6, NaClO.

4. Trng hp no sau y khngdn in c ?

a. KCl rn, khan. c. Nc sng, h, ao.

b. Nc bin. d. Dung dch KCl trong nc.

5. Cht no di y khngin li ra ion khi ho tan trong nc ?

A. MgCl2, B. HClO3, C. C6H12O6 (glucoz), D. Ba(OH)2,

6. Dung dch no sau y khngdn in c ?

A. HCl trong C6H6 (benzen). B. Ca(OH)2 trong nc.

B. CH3COONa trong nc. D. NaHSO4 trong nc.

7. Vi cht in li l hp cht ion v hp cht cng ho tr phn cc th c ch ca qutrnh in li nh th no ?

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Phn loi cc cht in liBI2

Hiu in li, cn bng in li l g,

Hiu th no l cht in li mnh v cht in li yu.

I in li

1. Th nghim

Chun b hai cc : mt cc ng dung dch HCl 0,10M, cc kia ng dung dch

CH3COOH 0,10M ri lp vo b dng c nh hnh 1.1. Khi ni cc u dy dn

in vi ngun in, ta thy bng n cc ng dung dch HCl sng hn so vi

bng n cc ng dung dch CH3COOH.

iu chng t rng : nng cc ion trong dung dch HCl ln hn nng cc ion trong dung dch CH3COOH, ngha l s phn t HCl in li ra ion nhiu

hn so vi s phn t CH3COOH in li ra ion.

2. in li

nh gi mc in li ra ion ca cht in li trong dung dch, ngi ta dng

khi nim in li.

in li (anpha) ca cht in li l t s gia s phn t phn li ra ion

(n) v tng s phn t ho tan (no).

o

n

n =

in li ca cc cht in li khc nhau nm trong khong 0 < 1. Khi mt

cht c = 0, qu trnh in li khng xy ra, l cht khng in li. in li

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th

ng

c biu din d

i dng phn trm. Th d, trong dung dch CH3COOH0,043M, c 100 phn t ho tan ch c 2 phn t in li ra ion, in li l :

2

100 = = 0,02 hay 2%

II Cht in li mnh v cht in li yu

1. Cht in li mnhCht in li mnh l cht khi tan trong nc(*), cc phn t ho tan u in li

ra ion.Vy cht in li mnh c = 1. l cc axit mnh, nhHCl, HNO3, HClO4,

H2SO4,... ; cc baz mnh, nhNaOH, KOH, Ba(OH)2... v hu ht cc mui.

Trong phng trnh in li ca cht in li mnh, ngi ta dng mt mi tn

ch chiu ca qu trnh in li. Th d :

Na2SO4 2Na+ + 24SO

V s in li ca Na2SO4 l hon ton, nn ta d dng tnh c nng ion do

Na2SO4 in li ra. Th d, trong dung dch Na2SO4 0,10M, nng ion Na+ l

0,20M v nng ion 24SO l 0,10M.

2. Cht in li yuCht in li yu l cht khi tan trong nc ch c mt phn s phn t ho

tan in li ra ion, phn cn li vn tn ti di dng phn t trong dung dch.

Vy in li ca cht in li yu nm trong khong 0 < < 1.

Nhng cht in li yu l cc axit yu, nh CH3

COOH, HClO, H2

S, HF,

H2SO3, H2CO3... ; cc baz yu, nh Bi(OH)3, Cr(OH)2 v.v... Trong phng trnh

in li ca cht in li yu, ngi ta dng hai mi tn ngc chiu. Th d :

(*) Tt c cc cht u t nhiu tan trong nc. Th d, 25oC ho tan ca BaSO4 l

1,0.105 mol/l, ca AgCl l 1,2.105 mol/l, ca CaCO3 l 6,9.105 mol/l, ca Fe(OH)2 l

5,8.106 mol/l.

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CH3COOH H+

+

CH3COO

a) Cn bng in li

S in li ca cht in li yu l qu trnh thun nghch, khi no tc in li

v tc kt hp cc ion to li phn t bng nhau, cn bng ca qu trnh in li

c thit lp. Cn bng in li cng lcn bng ng.

Ging nh mi cn bng ho hc khc, cn bng in li cng c hng s cn

bng K v tun theo nguyn l chuyn dch cn bng L Sa-t-li-.

b) nh hng ca s pha long n in liKhi pha long dung dch, in li ca cc cht in li u tng.

Th d, 25oC in li ca CH3COOH trong dung dch 0,100M l 1,32%,

trong dung dch 0,043M l 2% v trong dung dch 0,010M l 4,11%.

C th gii thch hin tng ny nh sau. Khi pha long dung dch, cc ion

dng v m ca cht in li cch xa nhau hn, t c iu kin va chm vo nhau

to li phn t, trong khi s pha long khng cn tr n s in li ca cc

phn t.

Bi tp

1. in li l g ? Th no l cht in li mnh, cht in li yu ? Ly mt s th d chtin li mnh, cht in li yu v vit phng trnh in li ca chng.

2. Cht in li mnh c in li

a. > 1. c. < 1.

b. = 1. D. 0 < < 1.

Hy chn p n ng.

3. Cht in li yu c in li

A. = 0. C. 0 < < 1.

B. = 1. D. < 0.

Hy chn p n ng.

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4. C hai cht in li AB v CD, trong A v C u c s oxi ho +I, chng l cc chttan c trong nc. Mt l cht in li mnh v mt l cht in li yu. Bng phng

php thc nghim no c th phn bit c chng ? M t phng php .

5. Tnh nng mol ca cation v anion do s in li to ra ca cc cht sau trong dungdch :

a) Ba(NO3)2 0,10M.

b) HNO3 0,02M.

c) KOH 0,01M.

6*. a) Chng minh rng in li c th tnh bng cng thc sau :

= o

C

C

Trong c Co l nng mol ca cht ho tan, C l nng mol ca cht ho tan

in li ra ion.

b) Tnh nng mol ca CH3COOH, CH3COO v H+ trong dung dch CH3COOH 0,043M

khi qu trnh in li trng thi cn bng, bit rng in li ca CH3COOH

bng 2%.

7. Cn bng sau tn ti trong dung dch : CH3COOH H+ +CH3COO

in li ca CH3COOH s bin i nh th no ?

a) Khi nh vo vi git dung dch HCl.b) Khi pha long dung dch.

c) Khi nh vo vi git dung dch NaOH.

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axit, baz v muiBi 3

Bit th no l axit, baz theo thuyt A-r-ni-ut v thuyt Bron-stt.

Bit phng trnh in li ca cc axit, baz v mui trong nc.

Bit hng s in li axit, hng s in li baz l g v s dng chng gii cc bi tp n gin.

I Axit v baz theo thuyt A-r-ni-ut

1. nh ngha

a) Axit l cht khi tan trong nc in li ra cation H+.

Th d : HCl H+ + Cl

CH3COOH H+ + CH3COO

Cc dung dch axit u c mt s tnh cht chung, l tnh cht ca cc cationH+ trong dung dch.

b) Baz l cht khi tan trong nc in li ra anion OH

.

Th d : NaOH Na++ OH

Cc dung dch baz u c mt s tnh cht chung, l tnh cht ca cc

anion OH

trong dung dch.

2. Axit nhiu nc, baz nhiu nc

a) Axit nhiu nc

T hai th d trn ta thy phn t HCl cng nhphn t CH3COOH trong dung

dch nc ch in li mt nc ra ion H+. l cc axit mt nc.

Nhng axit khi tan trong nc m phn t in li nhiu nc ra ion H+ l cc

axit nhiu nc. Th d :

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H3PO4 H+

+ 2H PO4

: K = 7,6.1013

2 4H PO H+ + 24HPO

: K = 6,2.1028

24HPO

H+ + 34PO : K = 4,4.103

13

Phn t H3PO4 in li ba nc ra ion H+, H3PO4 laxit ba nc.

b) Baz nhiu nc

Phn t NaOH khi tan trong nc ch in li mt nc ra ion OH, NaOH l

baz mt nc.

Nhng baz khi tan trong nc m phn t in li nhiu nc ra ion OH

l cc

baz nhiu nc. Th d :

Cr(OH)2 Cr(OH)+ + OH

Cr(OH) + Cr 2+ + OH

Phn t Cr(OH)2 in li hai nc ra ion OH, Cr(OH)2 lbaz hai nc.

3. Hiroxit lng tnh

Hiroxit lng tnh l hiroxit khi tan trong nc va c th in li nh

axit, va c th in li nh baz.

Th d, Zn(OH)2 l hiroxit lng tnh :

Zn(OH)2 Zn2+ +2OH

: in li kiu baz

Zn(OH)2 2H+ + Zn (22O

*) : in li kiu axit

th hin tnh axit ca Zn(OH)2 ngi ta thng vit n di dng H2ZnO2.

Mt s hiroxit lng tnh thng gp l Al(OH)3, Zn(OH)2, Pb(OH)2, Sn(OH)2,

Cr(OH)3, Cu(OH)2. Chng u tan t trong nc v lc axit, lc(**) baz u yu.

(*) Thc t trong dung dch tn ti ion [Zn(OH)4]2 :

Zn(OH)2 + 2H2O [Zn(OH) 4]2 + 2H+

(**) Lc axit hay lc baz c nh gi bng hng s cn bng in li K.

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II khi nim v Axit v baz theo thuyt Bron-stt(*)

1. nh ngha

Axit l cht nhng proton (H+).Baz l cht nhn proton.

Axit Baz + H +

Th d 1 : CH3COOH + H2O H3O+ +CH3COO

Trong phn ng ny, CH3COOH nhng H+ cho H2O, CH3COOHl axit ; H2O

nhn H+, H2O l baz. Theo phn ng nghch CH3COO

nhn H+, CH3COO

l

baz, cn H3O+ (ion oxoni) nhng H+, H3O

+ l axit.

Th d 2 : NH3 + H2O 4NH+ + OH

NH3 l baz, H2O l axit. Theo phn ng nghch 4NH+ l axit v OH

l baz.

Th d 3 : + H3HCO

2O H 3O+ + 23CO

v H3HCO

3O+ l axit, H2O v

23CO

l baz.

+ H3HCO

2O H2CO3 + OH

y v OH3HCO l baz, H2O v H2CO3

l axit. Vy l lng tnh.3HCO

Nhn xt: Phn t H2O, c th ng vai tr axit hay baz. Vy H2O l

chtlng tnh.

Theo thuyt Bron-stt, axit v baz c th l phn t hoc ion.

2. u im ca thuyt Bron-sttTheo thuyt A-r-ni-ut, trong phn t axit phi c hiro v trong nc in li ra

H+, trong phn t baz phi c nhm OH v trong nc in li ra OH. Vy thuyt

A-r-ni-ut ch ng cho trng hp dung mi l nc. Mt khc, c nhng cht

khng cha nhm OH, nhng l baz, nhNH3, cc amin(**) th thuyt A-r-ni-ut

khng gii thch c.

Thuyt Bron-stt tng qut hn, n p dng ng cho bt k dung mi n

o ckh nng nhng v nhn proton, c khi vng mt dung mi. Tuy nhin, ychng ta ch nghin cu tnh cht axit baz trong dung mi nc, nn c haithuyt u cho kt qu ging nhau.

(*) Trong mt s ti liu gi l thuyt Bron-stt Lau-ri (J. N. Brnsted, 1879 1947, nhho hc an Mch, T. Lowry, 1874 1936, nh ho hc Anh). Thuyt ny cng c tn lthuyt proton.

(**) Cc amin s hc phn cc cht hu c lp 12.

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III Hng s in li axit v baz

1. Hng s in li axitS in li axit yu trong nc l qu trnh thun nghch, trng thi cn bng

c th p dng biu thc hng s cn bng cho n. Th d :

CH3COOH H+ +CH3COO

(1) ; Ka =

3

3

H CH COO

CH COOH

+

Trong : [H+], [CH3COO] v [CH3COOH] l nng mol ca H

+, CH3COO

v CH3

COOH lc cn bng.

Cn bng trong dung dch CH3COOH c th vit :

3 2 3 3CH COOH H O H O CH COO+ + + (2) ;

[ ]3 3

a3

H O CH COOK

CH COOH

+ =

H2O trong cn bng (2) l dung mi, trong dung dch long nng ca H2Oc coi l hng s, nn khng c mt trong biu thc tnh K.

Phng trnh (1) c vit theo thuyt A-r-ni-ut, phng trnh (2) c vittheo thuyt Bron-stt. Hai cch vit ny cho kt qu ging nhau, ngha l gi tr Kanhnhau, v H+ v H3O

+ ch khc nhau v cch vit.

Ka l hng s in li axit.i vi axit xc nh, Ka ch ph thuc vo nhit .

Gi tr Ka ca axit cng nh, lc axit cng yu. Th d, 25oC, Ka ca

CH3COOH l 1,75.105 v ca HClO l 5,0.10

8. Vy lc axit ca HClO yu hn

ca CH3COOH, ngha l nu hai axit c cng nng mol v cng nhit th

nng mol ca H+ trong dung dch HClO nh hn.

2. Hng s in li baz

Th d, NH3 trong nc l baz yu : NH3 + H2O 4NH+ + OH

4b

3

[NH ][OH ]K

[NH ]

+

=

[ ], [OH4

NH+] v [NH3] l nng mol ca 4NH

+ , OH

v NH3 lc cn bng ;

Kb l hng s in li baz.Kb ca mt baz xc nh ch ph thuc vo nhit .

Gi tr Kb ca baz cng nh, lc baz ca n cng yu.

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IV Mui

1. nh ngha

Mui l hp cht, khi tan trong nc in li ra cation kim loi (hoc cation

) v anion gc axit.4

NH+

Th d : (NH4)2SO4 2 4NH+ + 2

4SO

NaHCO3 Na+ +

3HCO

Mui m anion gc axit khng cn hiro c kh nng in li ra ion H+ (hiro

c tnh axit)

(*)

c gi l

mui trung ho

. Th d, NaCl, (NH4)2SO4, Na2CO3.Nu anion gc axit ca mui vn cn hiro c kh nng in li ra ion H +, th

mui c gi lmui axit. Th d, NaHCO3, NaH2PO4, NaHSO4.

Ngoi ra c mt s mui phc tp thng gp nh mui kp : NaCl.KCl ;

KCl.MgCl2.6H2O ;... phc cht : [Ag(NH3)2]Cl ; [Cu(NH3)4]SO4 ;...

2. S in li ca mui trong nc

Hu ht cc mui (k c mui kp) khi tan trong nc in li hon ton ra

cation kim loi (hoc cation4

NH+ ) v anion gc axit (tr mt s mui nhHgCl2,

Hg(CN)2 v.v... l cc cht in li yu). Th d :

K2SO4 2K+ + 2

4SO

NaCl . KCl Na+ + K+ + 2Cl

NaHSO3 Na+ +

3HSO

Nu anion gc axit cn cha hiro c tnh axit, th gc ny in li yu ra H+.Th d

H3

HSO + + 23

SO

Phc cht khi tan trong nc in li hon ton ra ion phc (ion phc nm trongdu mc vung), sau ion phc in li yu ra cc cu t thnh phn. Th d :

[Ag(NH3)2]Cl [Ag(NH3)2]+ + Cl

[Ag(NH3)2]+ Ag+ + 2NH3

(*) Trong gc axit ca mt s mui nh Na2HPO3, NaH2PO2, vn cn hiro, nhng l muitrung ho v cc hiro khng c tnh axit.

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B

i tp1. Pht biu cc nh ngha axit v baz theo thuyt A-r-ni-ut v thuyt Bron-stt. Ly

cc th d minh ho.

2. Th no l baz mt nc v nhiu nc, axit mt nc v nhiu nc, hiroxit lng tnh, muitrung ho, mui axit ? Ly cc th d v vit phng trnh in li ca chng trong nc.

3. Hng s in li axit, hng s in li baz l g ? Ly th d.

4. Kt lun no di y l ng theo thuyt A-r-ni-ut ?

A. Mt hp cht trong thnh phn phn t c hiro l axit.

B. Mt hp cht trong thnh phn phn t c nhm OH l baz.

C. Mt hp cht trong thnh phn phn t c hiro v in li ra H+ trong nc l axit.D. Mt baz khng nht thit phi c nhm OH trong thnh phn phn t.

5. Theo thuyt Bron-stt th cu tr li no sau y l ng ?

A. Trong thnh phn ca baz phi c nhm OH.

B. Axit hoc baz c th l phn t hoc ion.

C. Trong thnh phn ca axit c th khng c hiro.

D. Axit hoc baz khng th l ion.

6. Chn cu tr li ng trong s cc cu di y :

A. Gi tr Ka ca mt axit ph thuc vo nng .

B. Gi tr Ka ca mt axit ph thuc vo p sut.C. Gi tr Ka ca mt axit ph thuc vo nhit .

D. Gi tr Ka ca axit cng nh lc axit cng mnh.

7. Vit phng trnh in li ca cc cht sau trong dung dch : K2CO3, NaClO, Na2HPO4,

Na3PO4, Na2S, NaHS, Sn(OH)2.

8. Hy cho bit cc phn t v ion sau l axit, baz hay lng tnh theo thuyt Bron-stt :

HI ; CH3COO, , NH3

2 4 4 4H PO , PO , NH

+3 ; S

2 ;2

4HPO

. Minh ho bng phn ng ho

hc ca chng trong dung dch nc.

9. Vit biu thc hng s in li axit Ka hoc hng s in li baz Kb cho cc trng hpsau : HF ; CH3COO

; ; F4

NH+ .

10. C hai dung dch sau :

a) CH3COOH 0,10M (Ka = 1,75.105). Tnh nng mol ca ion H+.

b) NH3 0,10M (Kb = 1,80.105). Tnh nng mol ca ion OH.

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S in li ca nc. ph.Cht ch th axit - bazBi 4

Hiu tch s ion ca nc l g.Hiu cch nh gi axit v kim ca cc dung dch theo

nng ion H+ v pH.Bit mu ca mt s cht ch th trong dung dch cc khong

pH khc nhau.

I nc l cht in li rt yu

1. S in li ca nc

Bng dng c o nhy, ngi ta thy nc cng dn in nhng cc k yu, v

nc l cht in li rt yu : H2O H+ + OH

(1)

2. Tch s ion ca nc

T phng trnh (1) ta c th vit c biu thc hng s cn bng K ca

phn ng :2

[H ][OH ]K

[H O]

+ =

Thc nghim xc nh c rng, nhit thng c 555 triu phn t nc

ch c mt phn t in li ra ion, nn [H2O] c coi l hng s. T , t :

= K[H2

H OK 2O] = [H+].[OH

]

Hng s c gi ltch s ion ca nc, tch s ny l hng s nhit

xc nh. 252

H OK

oC :

= [H2

H OK +].[OH] = 1,0.10

14

Tch s ion ca nc l hng s c trong dung dch long ca cc cht khc nhau.

V mt phn t H2O phn li ra mt ion H+ v mt ion OH

, nn trong nc:

[H+] = [OH] = 141,0 .10 = 1,0.10

7 mol/l.

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Nc l mi trng trung tnh, nn c th nh ngha mi trng trung tnh l

mi trng trong [H+] = [OH

] = 1,0.107

M.

3. ngha tch s ion ca nc

a) Mi trng axit: Khi ho tan axit vo nc, nng H+ tng, nn nng

OHphi gim sao cho tch s ion ca nc khng i.

Th d, ho tan axit vo nc nng H+ bng 1,0.103 mol/l th nng

OH

l : [OH] =

141,0.10

H

+

=14

3

1,0.10

1,0.10

= 1,0.10

11 mol/l.

Vy mi trng axit l mi trng trong [H+] > [OH

] hay [H+] > 1,0.107

M.

b) Mi trng kim(*):Khi ho tan baz vo nc, nng OH

tng, nn nng

H+ phi gim sao cho tch s ion ca nc khng i. Th d, ho tan baz vo

nc nng OH

bng 1,0.105M th nng H+ l :

[H+] =141,0.10

OH

=14

5

1,0.10

1,0.10

= 1,0.10

9 mol/l

Vy mi trng kim l mi trng trong : [H+] < [OH

] hay [H+] 1,0.10

7

MMi trng kim : [H+] < 1,0.10

7M

II Khi nim v pH. Cht ch th axit baz

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1. Khi nim v pH

Nh thy trn, da vo nng H+ trong dung dch nc c th nh

gi c axit v kim ca dung dch. Nhng dung dch thng dng c

nng H+ nh, trnh ghi nng H+ vi s m m, ngi ta dng pH vi

quy c nh sau :

[H+] = 1,0.10pH(*)M hoc nu [H+] = 1,0.10

aM th pH = a.

Th d : [H+] = 1,0.101M pH = 1,0 : mi trng axit.

[H+] = 1,0.107M pH = 7,0 : mi trng trung tnh.

[H+] = 1,0.1011M pH = 11,0 : mi trng kim.

Thang pH thng dng c gi tr t 0 n 14 :

Gi tr pH c ngha to ln trong thc t. Chng hn, pH ca mu ngi v ngvt c gi tr gn nhkhng i. Thc vt c th sinh trng bnh thng ch khi gi

tr pH ca dung dch trong t trong khong xc nh c trng cho mi loi cy.

Tc n mn kim loi trong nc t nhin ph thuc rt nhiu vo pH ca nc

m kim loi tip xc.

2. Cht ch th axit baz

Cht ch th axitbaz l cht c mu bin i ph thuc vo gi tr pH ca

dung dch. Th d, mu ca hai cht ch th axit baz lqu vphenolphtalein

trong cc khong pH khc nhau c a ra trong bng 1.1.

(*) Khi baz tan trong nc to thnh dung dch c tnh kim. Mi trng ca n c gil mi trng kim.

(*) V mt ton hc pH = lg[H+

]

(**) Trong dung dch xt c mu hng b mt.

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Bng 1.1. Mu ca qu v phenolphtalein trong dung dch cc khong pH

khc nhau

Trn ln mt s cht ch th c mu bin i k tip nhau theo gi tr pH, ta

c hn hp cht ch th axitbaz vn nng. Dng bng giy tm dung dch

hn hp ny c th xc nh c gi tr gn ng pH ca dung dch. xc nh gi tr tng i chnh xc pH ca dung dch ngi ta dng my

o pH.

Bi tp

1. Pht biu cc nh ngha mi trng axit, trung tnh v kim theo nng H+ v pH 25oC.

2. Mt dung dch c [OH] = 2,5.1010M. Mi trng ca dung dch l

A. axit B. kim C. trung tnh D. khng xc nh c

Hy chn p n ng.3. Trong dung dch HNO3 0,010M, tch s ion ca nc nhit bt k l :

A. [H+] [OH] = 1,0.1014. B. [H+] [OH] > 1,0.1014.

C. [H+] [OH] < 1,0.1014. D. Tu thuc vo nhit .

Hy chn p n ng.

4. Mt dung dch c [OH] = 4,2.103M, nh gi no di y l ng ?

A. pH = 3 ; B. pH = 4 ; C. pH < 3 ; D. pH > 4.

5. Mt dung dch c pH = 5, nh gi no di y l ng ?

A. [H+] = 2,0.105M ; B. [H+] = 5,0.104M ;

C. [H+] = 1,0.105M ; D. [H+] = 1,0.104M.

6. Ka(CH3COOH) = 1,75.105 ; Ka(HNO2) = 4,0.10

4. Nu hai axit c nng bngnhau v cng nhit , khi qu trnh in li trng thi cn bng, nh gi n odi y l ng ?

A. B.>3 2

+ +CH COOH HNO[H ] [H ]

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7. Hai dung dch axit a ra cu 9 cng nng mol v cng nhit , axit no c in li ln hn?

8. Cht ch th axit baz l g ? Hy cho bit mu ca qu v phenolphtalein trong dungdch cc khong pH khc nhau.

9. Cn bao nhiu gam NaOH pha ch 300 ml dung dch c pH = 10,0 ?

10. a) Tnh pH ca dung dch cha 1,46 g HCl trong 400,0 ml.

b) Tnh pH ca dung dch to thnh sau khi trn 100,0 ml dung dch HCl 1,000M vi400,0 ml dung dch NaOH 0,375M.

T liu pH v s su rng

Rng c bo v bi lp men cng, dy khong 2mm. Lp men ny l hp cht

Ca5(PO4)3 OH v c to thnh bng phn ng :

5Ca2+ + 3 + OH 34PO Ca5(PO4)3OH (1)

Qu trnh to lp men ny l s bo v t nhin ca con ngi chng li bnhsu rng.

Sau ba n, vi khun trong ming tn cng cc thc n cn lu li trn rng to thnhcc axit hu c nhaxit axetic, axit lactic. Thc n vi hm lng ng cao to iu kintt nht cho vic sn sinh ra cc axit .

Lng axit trong ming tng, pH gim, lm cho phn ng sau xy ra : H+ + OH

H2O

Khi nng OH gim, theo nguyn l L Sa-t-li-, cn bng (1) chuyn dch theochiu nghch v men rng b mn, to iu kin cho su rng pht trin.

Bin php tt nht phng su rng l n thc n t chua, t ng, nh rng sau khi n.

Ngi ta thng trn vo thuc nh rng NaF hay SnF2, v ion F

to iu kin cho phnng sau xy ra :

5Ca2+ + 3 34PO + F

Ca5(PO4)3F

Hp cht Ca5(PO4)3 F l men rng thay th mt phn Ca5(PO4)3OH.

nc ta, mt s ngi c thi quen n tru rt tt cho vic to men rng theo phn

ng (1), v trong tru c vi ti Ca(OH)2, cha Ca2+ v OH

lm cho cn bng (1) chuyn

dch theo chiu thun.

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Luyn tpAxit, baz v mui

Bi 5

Cng c kin thc v axit, baz v mui.

Rn luyn k nng tnh pH ca cc dung dch axit mt nc vbaz mt nc.

I kin thc cn nm vng

1. Axit khi tan trong nc in li ra cation H+ (theo thuyt A-r-ni-ut) hoc axit l

cht nhng proton H+ (theo thuyt Bron-stt).

Baz khi tan trong nc in li ra anion OH (theo thuyt A-r-ni-ut) hoc baz

l cht nhn proton H+ (theo thuyt Bron-stt).

2. Cht lng tnh va c th th hin tnh axit, va c th th hin tnh baz.

3. Hu ht cc mui khi tan trong nc, in li hon ton ra cation kim loi (hoc

cation ) v anion gc axit.4NH+

Nu gc axit cn cha hiro c tnh axit, th gc in li yu ra cation H+ v

anion gc axit.

4. Hng s in li axit Ka v hng s in li baz Kb l cc i lng c trng

cho lc axit v lc baz ca axit yu v baz yu trong nc.

5. Tch s ion ca nc l = [H2

H OK+] [OH] = 1,0.1014( 25oC). N l hng s

trong nc cng nh trong dung dch long ca cc cht khc nhau.

6. Gi tr [H+] v pH c trng cho cc mi trng :

Mi trng trung tnh : [H+] = 1,0.107M hay pH = 7,0

Mi trng axit : [H+] > 1,0.107M hay pH < 7,0

Mi trng kim : [H+] < 1,0.107M hay pH > 7,0

7. Mu ca qu v phenolphtalein trong dung dch cc khong pH khc nhau

(xem bng 1.1) :

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II B

i tp1. Vit cc biu thc hng s in li axit Ka hoc hng s in li baz Kb ca

cc axit v baz sau : HClO, OCl, HNO2, 2NO

.

2. i vi dung dch axit yu HNO2 0,10M, nu b qua s in li ca nc, nh

gi no sau y l ng ?

A. pH > 1,0. B. pH = 1,0. C. [H+] > [ 2NO ] D. [H+] < [ ].2NO

3. i vi dung dch axit mnh HNO3 0,10M, nu b qua s in li ca nc,nh gi no sau y l ng ?

A. pH < 1,0. B. pH > 1,0. C. [H+] = [ 3NO ] D. [H+] > [ ]3NO

4. Khi pha long dung dch mt axit yu in li ca axit tng. kin nosau y l ng ?

A. Hng s in li axit Ka tng. B. Hng s in li axit Ka gim.

C. Hng s in li axit Ka khng i. D. Khng xc nh c.

5. a) Ho tan hon ton 2,4g Mg trong 100,0 ml dung dch HCl 3,0M. Tnh pHca dung dch thu c.

b) Tnh pH ca dung dch thu c sau khi trn 40,0 ml dung dch HCl 0,50Mvi 60,0 ml dung dch NaOH 0,50M.

6. Vit phng trnh in li ca cc cht sau trong nc : MgSO4, HClO3, H2S,

Pb(OH)2, LiOH, Cr(OH)2.

7. Ion no di y l axit theo thuyt Bron-stt ?

A. B. C.24SO .2Zn .+ 3NO

. D. 23SO .

8. Theo thuyt Bron-stt ion no di y l baz ?

A. Cu2+. B. Fe3+. C. OBr

D. Ag+.

9. Ion n

o sau y l

l

ng tnh theo thuyt Bron-stt ?A. Fe2+. B. Al3+. C. HS . D. Cl

.

10. Tnh nng mol ca ion H+ trong dung dch HNO2 0,10M, bit rng hng

s in li axit ca HNO2 l Ka = 4,0.104.

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Phn ng trao i ion trongdung dch cc cht in liBi 6

Hiu bn cht v iu kin xy ra phn ng trao i ion trongdung dch cc cht in li .Vit c phng trnh ion rt gn ca phn ng trong dungdch cc cht in li.

I iu kin xy ra phn ng trao i ion trong dung dch

cc cht in li

1. Phn ng to thnh cht kt ta

Th nghim. Nh dung dch natri sunfat (Na2SO4) vo ng nghim ng dung

dch bari clorua (BaCl2) thy kt ta trng ca BaSO4 xut hin :

Na2SO4 + BaCl2 2NaCl + BaSO4 (1)Gii thch. Na2SO4 v BaCl2 u d tan v in li mnh trong nc :

Na2SO4 2Na+ + 2

4SO

BaCl2 Ba

2+

+ 2Cl

Trong s bn ion c in li ra ch c cc ion Ba2+ v 24

SO kt hp c vi

nhau to thnh cht kt ta l BaSO4 (hnh 1.5), nn thc cht phn ng trong dungdch l :

Ba2+ + BaSO24

SO 4 (2)

Phng trnh (2) c gi lphng trnh ion rt

gnca phn ng (1).

Phng trnh ion rt gn cho bit bn cht caphn ng trong dung dch cc cht in li. Cch

chuyn phng trnh phn ng di dng phn tthnh phng trnh ion rt gn nh sau :

Chuyn tt c cc cht va d tan va in limnh thnh ion, cc cht kh, kt ta, in li yu nguyn dng phn t. Phng trnh thu c lphng trnh ion y . Th d, i vi phn ng(1) ta c :

Hnh 1.5. Phn ng to chtkt ta BaSO4.

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2Na

+

+ + Ba2

4SO 2+

+ 2Cl

BaSO4 + 2Na+

+2Cl

Lc b nhng ion khng tham gia phn ng, ta c phng trnh ion rt gn :Ba2+ + BaSO2

4SO 4

T phng trnh ny ta thy rng, mun iu ch BaSO4ch cn trn hai dung

dch, mt dung dch cha ion Ba2+ v dung dch kia cha ion 24

SO .

2. Phn ng to thnh cht in li yu

a)Phn ng to thnh nc

Th nghim. Chun b mt cc ng 25 ml dung

dch NaOH 0,10M. Nh vo vi git dung dch

phenolphtalein. Dung dch c mu hng (hnh 1.6).

Rt t t dung dch HCl 0,10M vo cc trn, va rt

va khuy cho n khi mt mu. Phn ng nh sau :

HCl + NaOH NaCl + H2O

Gii thch. NaOH v HCl u d tan v in li

mnh trong nc : Hnh 1.6. Mu ca phenolphtalein

trong mi tr

ng kimNaOH Na+ + OH

HCl H+

+ Cl

Cc ion OH

trong dung dch NaOH lm cho phenolphtalein chuyn sang mu

hng. Khi cho dung dch HCl vo dung dch NaOH, ch c cc ion H+ ca HCl

phn ng vi cc ion OH

ca NaOH to thnh cht in li rt yu l H2O.

Phng trnh ion rt gn l : H+ + OH H2O

Khi mu ca dung dch trong cc mt, ngha l H+ phn ng ht vi OH

ca NaOH.

Phn ng gia dung dch axit v hiroxit c tnh baz rt d xy ra v to thnh

cht in li rt yu l H2O.

Chng hn, Mg(OH)2 t tan trong nc, nhng d dng tan trong dung dch

axit mnh :

Mg(OH)2 (r) + 2H+ Mg2+ + 2H2O

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b) Phn ng to thnh axit yu

Th nghim. Nh dung dch HCl vo ng nghim ng dung dch CH3COONas to thnh axit yu l CH3COOH.

HCl + CH3COONa CH3COOH + NaClGii thch. HCl v CH3COONa l cc cht d tan v in li mnh :

HCl H+ + Cl

CH3COONa Na++ CH3COO

Trong dung dch, cc ion H+ s kt hp vi cc ion CH3COO

to thnh chtin li yu l CH3COOH. Phng trnh ion rt gn :

CH3COO

+ H+ CH3COOH

3. Phn ng to thnh cht kh

Th nghim. Rt dung dch HCl vo cc ng dung dch Na2CO3 ta thy c btkh thot ra :

2HCl + Na2CO3 2NaCl + CO2 + H2OGii thch. HCl v Na2CO3 u d tan v in li mnh :

HCl H+ + Cl

Na2CO3 2Na+ + 23CO

Cc ion H+ v trong dung dch kt hp vi nhau to thnh axit yu l

H

23CO

2CO3. Axit ny khng bn b phn hu ra CO2 v H2O :

3 3H HCO HCO+ +

3

2

3 2H HCO H CO+ +

2 3 2 2H CO CO H O +

Phng trnh ion rt gn :23 22H CO CO H O

+ + +

Phn ng gia mui cacbonat v dung dch axit rt

d xy ra, v va to thnh cht in li rt yu l H2O, va

to ra cht kh CO2 tch khi mi trng phn ng. Chnghn, cc mui cacbonat t tan trong nc, nhng d tantrong cc dung dch axit. Th d, vi (CaCO3) rt d tantrong dung dch HCl (hnh 1.7) :

CaCO3 (r) + 2HCl CO2 + H2O + CaCl2Phng trnh ion rt gn : Hnh 1.7. Phn ng to

thnh cht kh CO2CaCO3(r) + 2H+ Ca2+ + CO2 + H2O

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Th d 3. Khi ho

tan (CH3COO)2Pb trong n

c, c hai ion Pb

2+

v

CH3COO

u b thu phn. Mi trng l axit hay kim ph thuc vo

thu phn ca hai ion.

Th d 4. Nhng mui axit nh NaHCO3, KH2PO4, K2HPO4 khi ho tan

trong nc in li ra cc anion 23 2 4 4HCO , H PO ,HPO . Cc ion ny l lng

tnh. Chng cng phn ng vi H2O, mi trng ca dung dch tu thuc vobn cht ca anion.

Kt lun :a) Mui trung ho to bi cation ca baz mnh v gc axit yu, khi tan trong nc

gc axit yu b thu phn, mi trng ca dung dch l kim (pH > 7,0).

Th d, CH3COONa ; K2S ; Na2CO3.b)Mui trung ho to bi cation ca baz yu v gc axit mnh, khi tan trong

nc, cation ca baz yu b thu phn lm cho dung dch c tnh axit (pH < 7,0).

Th d, Fe(NO3)3, NH4Cl, ZnBr2.c)Mui trung ho to bi cation ca baz mnh v gc axit mnh, khi tan trong

nc khng b thu phn, mi trng ca dung dch vn trung tnh (pH = 7,0).

Th d NaCl, KNO3, KI.d)Mui trung ho to bi cation ca baz yu v anion ca gc axit yu, khi

tan trong nc c cation v anion u b thu phn. Mi trng ca dung dchph thuc vo thu phn ca hai ion.

Bi tp1. iu kin xy ra phn ng trao i ion trong dung dch cc cht in li l g ? Ly

cc th d minh ho.

2. Vit phng trnh ion rt gn ca cc phn ng (nu c) xy ra trong dung dch giacc cp cht sau :

a. Fe2(SO4)3 + NaOH b. KNO3 + NaCl

c. NaHSO3 + NaOH d. Na2HPO4 + HCl

e. Cu(OH)2 (r) + HCl g. FeS (r) + HCl

h. Cu(OH)2(r) + NaOH i. Sn(OH)2(r) + H2SO4

3. Hy iu ch kt ta CuS bng ba phn ng trao i ion khc nhau xy ra trong dungdch. T rt ra bn cht ca phn ng trong cc dung dch ny.

4. Dung dch cht no sau y l mi trng axit ?

A. NaF. B. Al(NO3)3. C. KI. D. K2S

5. Phng trnh ion rt gn ca phn ng cho bit

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A. nhng ion no tn ti trong dung dch.

B. nng nhng ion no trong dung dch ln nht.

C. bn cht ca phn ng trong dung dch cc cht in li.

D. khng tn ti cc phn t trong dung dch cc cht in li.

Hy chn cu tr li ng.

6. a) Dng phn ng ho hc loi b mt loi cation ra khi dung dch cha

NaNO3 v Ca(NO3)2.

b) Dng phn ng ho hc loi b mt loi anion ra khi dung dch cha KBr v

KNO3.

7. Mt trong cc nguyn nhn gy bnh au d dy do lng axit HCl trong qu cao.

gim bt lng axit, ngi ta thng ung NaHCO3. Gii thch bng phng trnh

phn ng xy ra di dng ion rt gn.

8. Khi nhng cp in cc vo cc ng dung dch H2SO4 trong b dng c nhhnh 1.1ri ni cc dy dn in vi ngun in, bng n sng r. Sau khi thm vo cc

mt lng dung dch Ba(OH)2, bng n sng yu i. Nu cho ddung dch Ba(OH)2

vo, bng n li sng r. Gii thch.

9. Vit phng trnh ho hc di dng phn t v ion rt gn ca phn ng trao i iontrong dung dch to thnh tng kt ta sau (hnh 1.8) :

a. CuS. b. CdS. c. MnS. d. ZnS. e. FeS.

Hnh 1.8

10. Dung dch cht no di y l mi trng kim ?

A. AgNO3. B. NaClO3. C. K2CO3. D. SnCl2.

11. Dung dch cht no di y l mi trng axit ?

A. NaNO3. B. KClO4. C. Na3PO4. D. NH4Cl.

12. Tnh nng H+ (mol/l) trong cc dung dch sau :

a) CH3COONa 0,10M (Kb ca CH3COO l 5,71.1010) ;

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b) NH4Cl 0,10M (K

aca l 5,56.10+

4NH 10).

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Luyn tpPhn ng trao i ion trongdung dchcc cht in li

Bi 7

Cng c kin thc v iu kin xy ra phn ng trao i iontrong dung dch cc cht in li.

Rn luyn k nng vit phng trnh ion rt gn ca cc phnng.

I Kin thc cn nm vng

1. Phn ng trao i ion trong dung dch cc cht in li ch xy ra khi c t nhtmt trong cc iu kin sau :

a. To thnh cht kt ta.

b. To thnh cht in li yu.

c. To thnh cht kh.

2. Phn ng thu phn ca mui l phn ng trao i ion gia mui ho tan v nc.Ch nhng mui cha gc axit yu hoc (v) cation ca baz yu mi b thu phn.

3. Phng trnh ion rt gn cho bit bn cht ca phn ng trong dung dch cc chtin li. Trong phng trnh ion rt gn ca phn ng, ngi ta lc b nhng ionkhng tham gia phn ng, cn nhng cht kt ta, in li yu, cht kh c ginguyn di dng phn t.

II Bi tp1. Vit phng trnh ion rt gn ca cc phn ng (nu c) xy ra trong dung dch

gia cc cp cht sau :

a. MgSO4 + NaNO3 b. Pb(NO3)2 + H2S

c. Pb(OH)2 + NaOH d. Na2SO3 + H2Oe. Cu(NO3)2 + H2O g. Ca(HCO2)2 + Ca(OH)2

h. Na2SO3 + HCl i. Ca(HCO3)2 + HCl

2. Phn ng trao i ion trong dung dch cc cht in li ch xy ra khi :

A. cc cht phn ng phi l nhng cht d tan.B. mt s ion trong dung dch kt hp c vi nhau lm gim nng

ca chng.

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C. cc sn phm khng phn ng c vi nhau to ra phn ng nghch.D. cc cht phn ng phi l nhng cht in li mnh.Hy chn cu tr li ng.

3. Rau qu kh c bo qun bng kh SO2 thng cha mt lng nh hp

cht c gc 23SO . xc nh s c mt ion 23SO

trong hoa qu, mt hc sinh

ngm mt t qu u trong nc. Sau mt thi gian lc ly dung dch ri cho tc

dng vi dung dch H2O2 (cht oxi ho), sau cho tc dng tip vi dung dch

BaCl2. Vit cc phng trnh ion rt gn th hin cc qu trnh xy ra.

4. Nhng ho cht sau thng c dng trong cng vic ni tr : mui n ;

gim ; bt n NH4

HCO3

; phn chua KAl(SO4

)2

.12H2

O ; mui iot (NaCl + KI).Hy dng cc phn ng ho hc phn bit chng. Vit phng trnh ion rt gnca cc phn ng.

5. Ho tan hon ton 0,1022g mt mui kim loi ho tr hai MCO3 trong 20,0 mldung dch HCl 0,080M. trung ho lng HCl d cn 5,64ml dung dchNaOH 0,10M. Tm xem M l kim loi g.

6. Mi trng ca dung dch cht no di y c pH = 7,0 ?

A. CaCl2. B. NaF. C. CuSO4. D. KBr

7. Dung dch cht no sau y c pH < 7,0 ?

A. KI. B. KNO3. C. FeSO4. D. NaNO2.

8. Dung dch cht no cu 7 c pH > 7,0 ?9. Vit phng trnh ho hc di dng phn t v ion rt gn ca phn ng

trao i ion trong dung dch to thnh tng kt ta sau (hnh 1.9) :

a. Cr(OH)3. b. Al(OH)3. c. Ni(OH)2.

10. Tnh nng mol ca H+ v OH

trong dung dch NaNO2 1,0M, bit

rng hng s in li baz ca 2NO l Kb = 2,5.1011.

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d) iu ch kt ta Cu(OH)2 bng cc dung dch CuSO4 v

NaOH. Ho

tan ktta bng dung dch NaOH c. Quan st cc hin tng xy ra.

Vit phng trnh ho hc ca cc phn ng xy ra trong cc th nghim didng phn t v ion rt gn.

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Chng2 nhm nit

Nh my phn m Bc Giang

Nhm nit gm nhng nguyn t no ? V tr ca chng trong bng tun

hon c lin quan nh th no vi cu to nguyn t v phn t ca chng ?

Cc n cht v hp cht ca nit, photpho c nhng tnh cht c bn no ?

Da trn c s l thuyt hc gii thch nhng tnh cht nh th no ?

Lm th no iu ch c nit, photpho v mt s hp cht quan trng

ca chng ?

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Khi qut v nhm nitBi 91 ti t

Bit c nhm nit gm nhng nguyn t no.

Bit c tnh cht ca cc nguyn t trong nhm lin quan

nh th no vi cu hnh electron nguyn t, bn knh nguynt v m in ca cc nguyn t .

I V tr ca nhm nit trong bng tun hon

Nhm nit gm cc nguyn t : nit(N), photpho (P), asen (As), antimon (Sb)

v bitmut (Bi). Chng u thuc cc nguyn t p.

Bng 2.1. Mt s tnh cht ca cc nguyn t nhm nit

Nit Photpho Asen Antimon Bitmut

S hiu nguyn t 7 15 33 51 83

Nguyn t khi 14,01 30,97 74,92 121,75 208,98

Cu hnh electron lpngoi cng

2s22p3 3s23p3 4s24p3 5s25p3 6s26p3

Bn knh nguyn t (nm) 0,070 0,110 0,121 0,141 0,146

m in 3,04 2,19 2,18 2,05 2,02

Nng lng ion ho thnht (kJ/mol)

1402 1012 947 834 703

II tnh cht chung ca cc nguyn t nhm nit

1. Cu hnh electron nguyn tLp electron ngoi cng ca nguyn t l ns2np3,c 5 electron

ns2np3

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trng thi c bn, nguyn t ca cc nguyn t nhm nit c 3 electronc thn, do trong mt s hp cht chng c ho tr ba.

i vi nguyn t ca cc nguyn t P, As, Sb v Bi trng thi kch thch,mt electron trong cp electron ca phn lp ns c th chuyn sang obitan d trng

ca phn lp nd.

Nh vy, trng thi kch thch nguyn t ca cc nguyn t ny c 5 electronc thn v chng c th c ho tr nm trong cc hp cht.

2. S bin i tnh cht ca cc n cht

a)Tnh oxi ho kh

Trong cc hp cht, cc nguyn t nhm nit c s oxi ho cao nht l +5.

Ngoi ra, chng cn c cc s oxi ho +3 v3. Ring nguyn t nit cn cthm cc s oxi ho +1, +2, +4.

Do c kh nng gim v tng s oxi ho trong cc phn ng ho hc, nnnguyn t cc nguyn t nhm nit th hin tnh oxi ho vtnh kh.Kh nngoxi ho gim dn t nit n bitmut, ph hp vi chiu gim m in cacc nguyn t nguyn t trong nhm.

b) Tnh kim loi phi kimi t nit n bitmut, tnh phi kim ca cc nguyn tgim dn, ng thi tnh

kim loi tng dn. Nit, photpho l cc phi kim. Asen th hin tnh phi kim tri

hn tnh kim loi. Antimon th hin tnh kim loi v tnh phi kim mc gn

nhnhau, cn bitmut tnh kim loi tri hn tnh phi kim.

3. S bin i tnh cht ca cc hp cht

a)Hp cht vi hiro

Tt c cc nguyn t nhm nit u to c cc hp cht kh vi hiro

(hirua), c cng thc chung l RH3. bn nhit ca cc hirua gim dn t

NH3 n BiH3. Dung dch ca chng khng c tnh axit.

b)Oxit v hiroxit

T nit n bitmut, tnh axit ca cc oxit v hiroxit tng ng gim dn ngthi tnh baz ca chng tng dn. bn ca cc hp cht vi s oxi ho +3 tng,

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cn bn ca cc hp cht vi s oxi ho +5 ni chung gim. Cc oxit ca nit v

photpho vi s oxi ho +5 (N2O5, P2O5) loxit axit, hiroxit ca chng l cc axit(HNO3, H3PO4). Trong cc oxit vi s oxi ho +3 th As2O3 l oxit lng tnh, tnh

axit tri hn tnh baz ; Sb2O3 l oxit lng tnh, tnh baz tri hn tnh axit ; cn

Bi2O3 l oxit baz, tan d dng trong dung dch axit v hu nh khng tan trong

dung dch kim.

Bi tp

1. Vit cu hnh electron y ca cc nguyn t asen, antimon v bitmut trng thic bn v trng thi kch thch.

2. Da vo m in ca cc nguyn t, hy gii thch :

a) Ti sao t nit n bitmut tnh phi kim ca cc nguyn t gim dn ?

b) Ti sao tnh phi kim ca nit li th hin yu hn so vi oxi v cng yu hn sovi flo ?

3. Nu mt s hp cht trong nit v photpho c s oxi ho 3, +3, +5.

4. Ti sao trong cc hp cht nit ch c ho tr ti a l 4, trong khi i vi cc nguynt cn li ho tr ti a ca chng l 5 ?

5. Lp cc phng trnh ho hc sau v cho bit As, Bi v Sb2O3 th hin tnh cht g :

a) As + HNO3(c) H3 AsO4 + NO2 + H2O

b) Bi + HNO3 Bi(NO3)3+ NO + H2O

c) Sb2O3 + HCl SbCl3 + H2O

d) Sb2O3 + NaOH NaSbO2 + H2O

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NitBi 10(1 t ti )

Hiu cu to phn t, cc tnh cht vt l v ho hc ca nit.

Bit phng php iu ch nit trong phng th nghim, trongcng nghip v ng dng ca nit.

I Cu to phn tNguyn t nit c cu hnh

electron 1s22s22p3, phn lpngoi cng c 3 electron cthn. Hai nguyn t nit lin ktvi nhau bng ba lin kt cngho tr khng c cc, to thnh

phn t N2.

II Tnh cht vt l iu kin thng, nit l cht kh khng mu, khng mi, khng v, hi nh

hn khng kh, ho lng 196oC, ho rn 210oC. Kh nit tan rt t trong

nc : 20oC, 1 lt nc ho tan c 0,015 lt kh nit. Nit khng duy tr schy v s sng.

III Tnh cht ho hc

V c lin kt ba vi nng lng lin kt ln (ENN = 946 kJ/mol) nn phn t

nit rt bn. nhit thng, nit kh tr v mt ho hc nhng nhit caonit tr nn hot ng hn v c th tc dng vi nhiu cht.

Nguyn t nit l phi kim hot ng, m in ca n ch nh hn min ca flo v oxi. Tu thuc vo m in ca cht phn ng m nit th hintnh oxi ho hay tnh kh. Tuy nhin, tnh oxi ho vn tri hn tnh kh.

1. Tnh oxi hoa) Tc dng vi hiro : nhit cao (trn 400oC), p sut cao v c cht xc

tc, nit tc dng trc tip vi hiro to ra kh amoniac. y l phn ng thunnghch v to nhit.

; H = 92 kJoo 3t , P

2 2 xtN 3H 2 NH

+ 3

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b) Tc dng vi kim loi

nhit thng, nit ch tc dng vi kim loi liti, to thnh liti nitrua :0

26Li N+ 3

32Li N

nhit cao, nit tc dng vi mt s kim loi nhCa, Mg, Al,...

3Mg + N2ot Mg3N2 (magie nitrua)

Trong cc phn ng vi hiro v kim loi, s oxi ho ca nit gim : nit thhin tnh oxi ho.

2. Tnh khTc dng vi oxi: nhit khong 3000oC (hoc nhit ca l h quang

in), nit kt hp trc tip vi oxi to ra kh nit monooxit NO :0

2 2N O+ ot ; H = +180 kJ

22 NO

+

y l phn ng thun nghch v thu nhit.

phn ng ny, s oxi ho ca nit tng, nitth hin tnh kh. Trong thin nhin kh NOc to thnh khi c cn ging (hnh 2.1).

Hnh 2.1. Trong cn ging, cc tiast cung cp nng lng cho phn

ng gia N2 v O2 to thnh NO

iu kin thng, kh NO khng mukt hp ngay vi oxi trong khng kh, to rakh nit ioxit NO2 mu nu .

2

22 NO O

+

+

4

22 NO

+

Cc oxit khc ca nit nh N2O, N2O3,

N2O5 khng iu ch c t phn ng trctip gia nit v oxi.

IV Trng thi t nhin v iu ch1. Trng thi t nhin

Trong t nhin, nit tn ti dng t do v dng hp cht. dng t do, nit chim khong 80% th tch ca khng kh. Nit thin

nhin l hn hp ca hai ng v : 14 (99,63%) v15 (0,37%).7 N 7N

dng hp cht, nit c nhiu trong khong vt natri nitrat (NaNO3) vi tngi ldim tiu natri. Nit cn c trong thnh phn ca protein, axit nucleic,... vnhiu hp cht hu c thin nhin.

2. iu cha) Trong cng nghip, nit c sn xut bng phng php chng ct phn

on khng kh lng. Sau khi loi b CO2 v hi nc, khng kh c holng di p sut cao v nhit thp. Nng dn nhit , n 196oC th nit si

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v c tch khi oxi lng v oxi c nhit si cao hn ( 183oC). Kh nit cvn chuyn trong cc bnh thp, nn di p sut 150 atm.

b) Trong phng th nghim. Ngi ta iu ch mt lng nh nit tinh khitbng cch un nng dung dch bo ho mui amoni nitrit (mui amoni ca axit

nitr HNO2) :

NH4NO2ot

N2 + 2H2O

C th thay mui amoni nitrit km bn bng dung dch ca natri nitrit (NaNO 2)v amoni clorua (NH4Cl) :

NH4Cl + NaNO2ot N2 + NaCl + H2O

V ng dng

Nguyn t nit l mt trong nhng thnh phn dinh dng chnh ca thc vt.Trong cng nghip, phn ln lng nit sn xut ra c dng tng hpamoniac, t sn xut phn m, axit nitric v.v... Nhiu ngnh cng nghip nhluyn kim, thc phm, in t,... s dng nit lm mi trng tr. Nit lng cdng bo qun mu v cc mu vt sinh hc khc.

Bi tp1. Ion nitrua N3 c cu hnh electron ging cu hnh electron nguyn t ca kh tr no,

ca ion halogenua v ca ion kim loi kim no ? Hy vit cu hnh electron ca chng.

2. Trnh by cu to ca phn t N2. V sao iu kin thng N2 l mt cht tr ? iu kin no N2 tr nn hot ng hn ?

3. Xut pht t nhit phn li thnh nguyn t (H) ca cc phn t cho di y, hy chobit iu kin thng cht no (nit, hiro, oxi, clo) tham gia phn ng ho hc khnht v cht no d nht ? V sao ?

N2 2N ; H = 946 kJ/mol

H2 2H ; H = 431,8 kJ/mol

O2 2O ; H = 491 kJ/mol

Cl2 2Cl ; H = 238 kJ/mol.

4. Nu nhng tnh cht ho hc c trng ca nit v dn ra nhng phn ng ho hc minh ho.

5. Bng th nghim no c th bit c nit c cha tp cht clo ; hiro clorua ; hirosunfua ? Hy vit phng trnh ho hc ca cc phn ng tng ng.

6. Trn 200 ml dung dch natri nitrit 3M vi 200 ml dung dch amoni clorua 2M ri unnng cho n khi phn ng thc hin xong. Xc nh th tch ca kh nit sinh ra (ktc)

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amoniac v mui amoni

Bi 11

(2 tit)

Bit c tnh cht vt l, ho hc ca amoniac v mui amoni.Bit r vai tr quan trng ca amoniac v mui amoni trongi sng v trong sn xut.Vn dng nguyn l chuyn dch cn bng gii thch cciu kin ca phn ng tng hp amoniac t nit v hiro.

A. amoniac (Nh3)

I cu to phn t

Do c ba electron c thn, nn

nguyn t nit trong phn t amoniac

to thnh ba lin kt cng ho tr vi ba

nguyn t hiro.

..H : N : H..

H

|H N H

H

Cng thc electron Cng thc cu to

Phn t NH3 c cu to hnh chp, vinguyn t nit nh, y l mt tam gic

m nh l ba nguyn t hiro (hnh 2.2).

Ba lin kt N H u l lin kt c cc,

cc cp electron chung u lch v pha

nguyn t nit. Do , NH3 l phn t c

cc : N c d in tch m, cc

nguyn t H c din tchdng.II tnh cht vt l

Amoniac l cht kh khng mu, mi khaiv xc, nh hn khng kh nn c th thu kh

NH3 bng cch y khng kh (p ngc bnh).

Hnh 2.2. S cu to ca phn tamoniac

Hnh 2.3. Th nghim v tnh tan

nhiu ca NH3 trong nc

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Kh NH3 tan rt nhiu trong n

c : 1 lt n

c 20

o

C ho

tan

c 800 lt khNH3. Th nghim hnh 2.3 chng minh tnh tan nhiu ca NH3 trong nc. Dotan nhiu trong nc, p sut ca kh NH3 trong bnh gim t ngt, nc trongcc b ht vo bnh qua ng thu tinh vut nhn, phun thnh cc tia nc cmu hng.

Amoniac tan trong nc to thnh dung dch amoniac. Dung dch amoniac

m c thng c nng 25% (D = 0,91 g/cm3).

III tnh cht ho hc

1. Tnh baz yua) Tc dng vi nc. Khi tan trong nc, mt phn nh cc phn t amoniac

kt hp vi ion H+ ca nc, to thnh ion amoni 4(NH )+ v ion hiroxit (OH

).

Ion OHlm cho dung dch c tnh baz, tuy nhin so vi dung dch kim mnh

(th d NaOH) cng nng , th nng ion OH nh hn nhiu.

Phng trnh ho hc : NH3 + H2O 4NH+ + OH

Trong dung dch, amoniac l mt baz yu : 25oC, hng s in li baz

Kb = 1,8.10-5. Dung dch amoniac lm cho phenolphtalein t khng mu chuyn

sang mu hng, qu tm chuyn sang mu xanh. Li dng tnh cht ny ngi tadng giy qu tm tm t nhn ra kh amoniac.

b) Tc dng vi axit.Amoniac (dng kh cng nhdung dch) kt hp d dng

vi ion H+ ca dung dch axit to thnh mui amoni.

Th d : 2NH3 + H2SO4 (NH4)2SO4

NH3 + H+ +4NH

Hnh 2.4. S to thnh "khi" amoni clorua.

Th nghim : t hai bnh m ntng dung dch HCl c v NH3 c,gn nhau th thy c "khi" mu trng

to thnh (hnh 2.4). "Khi" l nhnght nh li ti ca tinh th mui amoni

clorua NH4Cl. Mui ny c tothnh do kh amoniac v kh hiroclorua ho hp vi nhau :

NH3 (k) + HCl (k) NH4Cl (r)

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Phn ng ny cng c s dng nhn ra kh amoniac.

c) Dung dch amoniac c kh nng lm kt ta nhiu hiroxit kim loi khi tcdng vi dung dch mui ca chng.

Th d : Al3+ + 3NH3 + 3H2O Al(OH)3 + 43NH+

2. Kh nng to phc

Dung dch amoniac c kh nng ho tan hiroxit hay mui t tan ca mt s

kim loi, to thnh cc dung dchphc cht.

Th d : Cu(OH)2 + 4NH3 [Cu(NH3)4](OH)2

Cu(OH)2 + 4NH3 [Cu(NH3)4]2+ + 2OH

(xanh thm)

AgCl + 2NH3 [Ag(NH3)2]Cl

AgCl + 2NH3 [Ag(NH3)2]+ + Cl

S to thnh cc ion phc [Cu(NH3)4]2+, [Ag(NH3)2]

+,... xy ra do cc phn t

amoniac kt hp vi cc ion Cu2+, Ag+,... bng cc lin kt cho nhn gia cp

electron cha s dng ca nguyn t nit vi obitan trng ca ion kim loi.

3. Tnh kh

a) Tc dng vi oxi : Khi ttrong kh oxi, amoniac chy vingn la mu vng, to ra kh nitv hi nc (hnh 2.5).

3 0

3 2 2 24 NH 3O 2N 6H O

+ +

Khi t amoniac trong oxikhng kh c mt cht xc tc th

to ra kh NO v

nc :3 2

3 2 24NH 5O 4NO 6H O +

+ +

b) Tc dng vi clo : Dn kh

NH3 vo bnh cha kh clo, NH3 tbc chy to ra ngn la c "khi"trng. Hnh 2.5.Amoniac chy trong kh oxi

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3 0

3 2 22NH 3Cl N 6HCl

+ +

"Khi" trng l nhng ht NH4Cl sinh ra do kh HCl va to thnh ho hp vi NH3.

c) Tc dng vi oxit kim loi

Khi un nng, NH3 c th kh mt s oxit kim loi thnh kim loi, chng hn

NH3 kh CuO mu en to ra Cu mu , nc v kh N2 :

o3 0t23 22NH 3CuO 3Cu N 3H O

+ + +

IV ng dng

Amoniac c s dng sn xut axit nitric ; cc loi phn m nh

NH4NO3, (NH4)2SO4, ur,... ; iu ch hirazin N2H4 lm nhin liu cho tn la.

Amoniac lng c dng lm cht gy lnh trong my lnh.

V iu ch

1. Trong phng th nghimKh amoniac c iu ch bng cch cho mui amoni tc dng vi kim, th

d Ca(OH)2, v un nng nh. Th d :

2NH4Cl + Ca(OH)2ot

2NH3 + CaCl2 + 2H2O.

Mun iu ch nhanh mt lng nh kh amoniac, ngi ta thng un nng

dung dch amoniac m c. lm kh kh, ngi ta cho kh NH3 va c to

thnh c ln hi nc i qua bnh ng vi sng (CaO).

2. Trong cng nghip

Amoniac c tng hp t kh nit v kh hiro theo phn ng :

N2(k) + 3H2(k) 2NH3(k) ; H = 92 kJ

y l phn ng thun nghch v to nhit. Theo nguyn l chuyn dch cn

bng L Sa-t-li-, mun cho cn bng chuyn dch v pha to thnh amoniac cn

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phi h nhit v tng p sut. Tuy nhin, nu nhit thp qu th phn ng

xy ra rt chm v nu p sut cao qu th i hi thit b cng knh v phc tp.

Trn thc t, ngi ta thng thc hin phn ng nhit khong 450 500oC,

p sut khong 200 300 atm v dng cht xc tc l st kim loi c trn thm

Al2O3, K2O,... lm cho cn bng nhanh chng c thit lp. cc iu kin

nh trn, hiu sut chuyn ho thnh NH3 cng ch t ti 20 25%.

Hnh 2.6. S thit b tng hp amoniac trong cng nghip

Hn hp kh N2 v H2 (t l mol 1 : 3) c nn p sut cao v a vo thptng hp (hnh 2.6). Trong thp ny, amoniac c to thnh cc iu kin nhit, p sut v cht xc tc thch hp nu trn. Hn hp kh i ra t thp tng

hp (gm c N2, H2 v NH3)c dn n thp lm lnh. y, kh amoniac holng v c tch ring ra, cn hn hp kh N2 v H2 cha phn ng c a trli thp tng hp.

B. Mui AmoNII Tnh cht vt l

Mui amoni l nhng cht tinh th ion, phn t gm cation amoni vanion gc axit. Tt c cc mui amoni u d tan trong nc v khi tan in li

hon ton thnh cc ion. Ion

4NH+

4NH+ khng c mu.

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II Tnh cht ho hc

1. Tc dng vi baz kimDung dch m c ca mui amoni tc dng vi dung dch kim khi un nng

s cho kh NH3 bay ra.

Th d : (NH4)2SO4 + 2NaOHot 2NH3 + Na2SO4 + 2H2O

NH 4 3 2OH NH H O+ + +

Ion nhng H4NH+ + cho ion OH

, vy trong dung dch ion l mt axit.

Phn ng n

y

c s dng nhn bit ion

4NH+

4NH

+

.Ngoi ra, mui amoni cn c th tham gia phn ng trao i vi dung dch ccmui khc.

2. Phn ng nhit phn

Khi un nng, cc mui amoni d b nhit phn hu, to ra cc sn phm khc nhau.Sn phm ca s phn hu c quyt nh ch yu bi bn cht ca axit to nn mui.

Mui amoni ca axit d bay hi khi un nng b phn hu thnh amoniac.Th d :

Tinh th NH4Cl c un nng trong ng nghim (hnh 2.7) s phn hu thnh

kh NH3 v kh HCl :

NH4Cl (r) NH

ot 3(k) + HCl (k)

Khi bay ln ming ng nghim gp nhit thp hn, hai kh ny ho hp vi

nhau to li tinh th NH4Cl mu trng bm ln thnh ng.

Cc mui amoni cacbonat v amonihirocacbonat b phn hu chm ngay nhit

thng, gii phng kh NH3 v kh CO2

Hnh 2.7. S phn hu ca NH4Cl

(NH4)2CO3 NH3 + NH4HCO3

NH4HCO3 NH3 + CO2 + H2OTrong thc t ngi ta thng dng mui

NH4HCO3 lm cho bnh tr nn xp.

Mui amoni ca axit c tnh oxi honh axit nitr, axit nitric khi b nhit phn

cho ra N2, N2O (init oxit) v nc.

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Th d : NH4NO2

N2 + 2H2ONH4NO3 N2O + 2H2O

Nhng phn ng ny c s dng iu ch cc kh N2 v N2O trongphng th nghim.

Bi tp1. M t v gii thch hin tng th nghim chng minh tnh tan nhiu ca kh amoniac

trong nc.

2. C 5 bnh ng ring bit 5 cht kh : N2, O2, NH3, Cl2 v CO2. Hy a ra mt thnghim n gin nhn ra bnh ng kh NH

3.

3. Nu tnh cht ho hc c trng v nhng ng dng ca amoniac. Ti sao ngi ta niamoniac l mt baz yu ?

4. Dung dch amoniac c th ho tan c Zn(OH)2 l doA. Zn(OH)2 l hiroxit lng tnh.

B. Zn(OH)2 l mt baz t tan.

C. Zn(OH)2 c kh nng to thnh phc cht tan, tng t nhCu(OH)2.

D. NH3 l mt hp cht c cc v l mt baz yu.

Hy chn cu ng.

5. Vit phng trnh ho hc ca cc phn ng thc hin s chuyn ho sau :

Kh A+

2H O

dung dch AHCl+

BNaOH+

kh A+

3HNO

Cnung

D + H2O6. Cho cn bng ho hc :

N2(k) + 3 H2(k) 2NH3(k) ; H = -92 kJ

Cn bng trn s chuyn dch theo chiu no (c gii thch) khi :

a) tng nhit ;

b) ho lng amoniac tch amoniac ra khi hn hp phn ng ;

c) gim th tch ca hn hp phn ng.

7. C th phn bit mui amoni vi cc mui khc bng cch cho n tc dng vi kimmnh, v khi

A. thot ra mt cht khi mu lc nht.

B. thot ra mt cht kh khng mu, rt xc, lm xanh giy qu tm m.C. thot ra mt cht kh mu nu , lm xanh giy qu tm m.

D. thot ra cht kh khng mu, khng mi.

Hy chn p n ng.

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Axit Nitric v mui nitratBi 12

Bit cu to phn t, tnh cht vt l v hiu ng tch cht ho hcca axit nitric v mui nitrat.

Bit phng php iu ch axit nitric trong phng th nghimv sn xut axit nitric trong cng nghip.

Rn luyn k nng vit phng trnh phn ng oxi ho kh.

A. Axit nitric (HNO3)

I Cu to phn t

Phn t HNO3 c cu to :

Trong hp cht HNO3,nguyn t nit c s oxi ho cao nht l +5.

II Tnh cht vt l

Axit nitric tinh khit l cht lng khng mu, bc khi mnh trong khng kh

m, khi lng ring bng 1,53 g/cm3, si 86oC. Axit nitric khng bn lm : khiun nng b phn hu mt phn theo phng trnh :

4HNO3 4NO2 + O2 + 2H2O

Phn ng ny cng xy ra iu kin thng, c bit khi c nh sng mt tri.Kh nit ioxit tan vo dung dch axit, lm cho dung dch c mu vng.

Axit nitric tan trong nc theo bt k t l no. Trn thc t thng dng loi

axit c c nng 68%, D = 1,40 g/cm3.

III Tnh cht ho hc

1. Tnh axit

Axit nitric l mt trong s cc axit mnh nht, trong dung dch long n phn li

hon ton thnh H+ v . Dung dch HNO3NO

3 c y tnh cht ca dung dch

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axit : lm qu tm i thnh mu , tc dng vi oxit baz v baz to thnhmui nitrat v nc, tc dng vi mui ca axit yu hn. Th d :

CuO + 2HNO3 Cu(NO3)2 + H2O

Ca(OH)2 + 2HNO3 Ca(NO3)2 + 2H2O

CaCO3 + 2HNO3 Ca(NO3)2 + CO2 + H2O

2. Tnh oxi ho

Axit nitric l mt trong nhng axit c tnh oxi ho mnh. Tu thuc vo nng

ca axit v bn cht ca cht kh m HNO3 c th b kh n mt s sn phm

khc nhau ca nit.a) Vi kim loi

Do ion trong phn t HNO3NO

3 c kh nng oxi ho mnh hn ion H+, nn

HNO3 oxi ho c hu ht cc kim loi, k c cc kim loi c tnh kh yu nhCu, Ag,..., tr Au v Pt. Khi , kim loi b oxi ho n mc oxi ho cao nht v tora mui nitrat.

Khi tc dng vi kim loi c tnh kh yu nh Cu, Pb,

Ag,... HNO3 c b kh n NO2 (hnh 2.8), cn HNO3 longb kh n NO. Th d :

0 5 2 4

3 3 2 2 2Cu 4HNO (c) Cu(NO ) 2NO 2H O

+ + +

+ + +

2+

0 5 2 2

3 3 23Cu 8HNO (long) 3 C u(NO ) 2NO 4H O+ + +

+ +

Hnh 2.8. Phn ngca Cu vi HNO3 c

Khi tc dng vi nhng kim loi c tnh kh mnh nh Mg, Zn, Al,... HNO3

long c th b kh n+1

2N O ,o

2N hoc3

4 3NH . Th d :NO

2

3 2+

0 5 3 1

23 3 38Al 30HNO (long) 8A l(NO ) 3N O 15H O+ + +

+ + +

0 5 3

3 3 2 44Zn 10HNO (rt long) 4Zn(NO ) NH NO 3H O+

+ +

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Fe, Al b th ng ho trong dung dch HNO3 c, ngui v to nn mt m

ngoxit bn trn b mt cc kim loi ny, bo v cho kim loi khng tc dng vi axit

nitric v nhng axit khc m trc chng tc dng d dng.

b) Vi phi kim

Khi un nng, axit nitric c c th oxi ho c nhiu phi kim nhC, S, P,... Khi

, cc phi kim b oxi ho n mc oxi ho cao nht, cn HNO3 b kh n NO2

hoc NO tu theo nng ca axit. Th d :

0 5 6 4

3 2 4 2S 6HNO (c) H S O 6N O 2H O

+ + +

+ + + 2

2+

c) Vi hp cht

Khi un nng, axit nitric c th oxi ho c nhiu hp cht nh H2S, HI,

SO2, FeO, mui st (II),... Th d :

2 5 0 2

2 33H S 2HNO (long) 3S 2NO 4H O + +

+ +

Nhiu cht hu c b ph hu hoc bc chy khi tip xc vi HNO3 c.

IV ng dng

HNO3 l mt trong nhng ho cht c bn quan trng. Phn ln HNO3 sn xut

trong cng nghip c dng iu ch phn bn NH4NO3. HNO3 cn c dng

sn xut thuc n (th d trinitrotoluen TNT,...), thuc nhum, dc phm.

V iu ch

1. Trong phng th nghim

HNO3 c iu ch bng cch cho natri nitrat hoc kali nitrat tc dng vi

HNO3c, nng :

NaNO3(r) + H2SO4(c) HNO3 + NaHSO4

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Hi HNO3 thot ra

c dn v

o bnh,

c l

m lnh v

ng

ng t (hnh2.9). Phng php ny ch c dng iu ch mt lng nh HNO3 bc khi.

Hnh 2.9. iu ch HNO3 c trong phng th nghim

2. Trong cng nghip

HNO3 c sn xut t amoniac. Qu trnh sn xut gm ba giai on :

Oxi ho kh amoniac bng oxi khng kh nhit 850 900o C, c mt

cht xc tc l

hp kim platin (Pt) v

irii (Ir) :4NH3 + 5O2 4NO + 6H2O ; H = 907 kJ

Phn ng ny to nhit v xy ra gn nhhon ton.

Oxi ho NO thnh NO2. Hn hp cha NO c lm ngui v cho ho hp

vi oxi khng kh to thnh kh nit ioxit :

2NO + O2 2NO2

Chuyn ho NO2 thnh HNO3. Cho hn hp nit ioxit va to thnh v oxi

tc dng vi n

c, s thu

c dung dch axit nitric :4NO2 + 2H2O + O2 4HNO3

Dung dch HNO3 thu c c nng khng vt qu 60 62%. lm tng

nng ca HNO3, ngi ta chng ct dung dch HNO3 ny vi H2SO4 m c

trong cc thit b c bit. Khi thu c dung dch HNO3 c nng cao hn.

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B. Mui nitratMui nitrat l mui ca axit nitric. Th d, natri nitrat (NaNO3), ng (II) nitrat

(Cu(NO3)2),...

I Tnh cht ca mui nitrat

1. Tnh cht vt lTt c cc mui nitrat u tan nhiu trong nc v l cht in li mnh. Trong

dung dch, chng phn li hon ton thnh cc ion. Ion 3NO khng c mu, nn

mu ca mt s mui nitrat l do mu ca cation kim loi ca mui to nn. Thd Cu(NO3)2 c mu xanh.

Mt s mui nitrat nh NaNO3, NH4NO3 ... hp th hi nc trong khng khnn d b chy ra.

2. Tnh cht ho hcCc mui nitrat km bn vi nhit, chng b phn hu khi un nng. bn

nhit ca mui nitrat ph thuc vo bn cht ca cation kim loi to mui. Ni chung, mui nitrat ca cc kim loi hot ng mnh (kali, natri,...) b

phn hu thnh mui nitrit v oxi :

Th d : 2KNO3ot 2KNO2 + O2

Mui nitrat ca magie, km, st, ch, ng,... b phn hu thnh oxit kim loi

tng ng, NO2 v O2 :

Th d : 2Mg(NO3)2ot

2MgO + 4NO2 + O2 Mui nitrat ca bc, vng, thu ngn,... b phn hu thnh kim loi tng

ng, kh NO2 v O2.

Th d : 2AgNO3ot

2Ag + 2NO2 + O2 nhit cao, mui nitrat phn hu ra oxi nn chng l cc cht oxi ho

mnh. Khi cho than nng vo mui kali nitrat nng chy, than bng chy. Hnhp mui nitrat nng chy v cht hu c d bt chy v chy mnh.

3. Nhn bit ion nitrat

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Trong mi tr

ng trung tnh, ion 3NO

khng c tnh oxi ho. Khi c mt ionH+, ion th hin tnh oxi ho ging nhHNO3NO

3. V vy nhn ra ion

ngi ta un nng nh dung dch cha

3NO ,

3NO vi ng kim loi v H2SO4 long :

3Cu + 8H+ + 32NO 3Cu2+ + 2NO + 4H2O

(xanh) (khng mu)

2NO + O2 2(nu )2NO

Phn ng to dung dch mu xanh v kh mu nu thot ra.

II ng dng ca mui nitrat

Cc mui nitrat c s dng ch yu lm phn bn ho hc (phn m)

trong nng nghip, th d NH4NO3,NaNO3, KNO3, Ca(NO3)2.

Kali nitrat cn c s dng ch thuc n en (thuc n c khi). Thuc n

en cha 75% KNO3, 10% S v 15% C.

C. Chu trnh ca nit trong t nhin

Nguyn t nit rt cn cho s sng trn Tri t. Trong t nhin lun lun din

ra cc qu trnh chuyn ho nit t dng ny sang dng khc theo mt chu trnh

tun hon khp kn (hnh 2.10).

1. Cy xanh ng ho nit ch yu dng mui nitrat v mui amoni, chuyn ho

thnh protein thc vt. ng vt ng ho protein thc vt, to ra protein ng vt.Cc cht thi do ng vt bi tit ra (phn, nc tiu,...) cng nhxc ng vt khicht i li chuyn thnh hp cht hu c cha nit. Nh nhng loi vi khun khcnhau c trong t, mt phn cc hp cht ny chuyn ho thnh amoniac, ri

thnh mui nitrat, phn cn li thot ra dng nit t do bay vo kh quyn. Khicc cht hu c (than g, than , than bn,...) b t chy, nit t do cng cthot ra.

Do cc qu trnh trn m lng nitrat trong t dn dn b cn kit, t ai trnn cn ci v cy ci s kh pht trin.

2. Trn thc t, c mt s qu trnh t nhin cho php b li mt phn lngnit b mt.

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Trong ma ging, khi c s phng in do sm st mt phn nit t do trong

kh quyn kt hp vi oxi to thnh kh NO, ri chuyn ho thnh HNO3 v theo

nc ma thm vo t. HNO3 chuyn thnh mui nitrat khi kt hp vi mui

cacbonat, th d canxi cacbonat, c trong t.

Mt s loi vi khun, c bit l cc vi khun c nh m sng r cy h uc kh nng hp th nit t kh quyn v chuyn ho thnh cc hp cht cha nit.

3. tng nng sut ma mng, lng nit chuyn t kh quyn vo t vn

khng th . Ngi ta c tnh lng nitrat ti sinh t nhin ch bng mt nalng nitrat b hp th. Do , cn phi bn vo t nhng hp cht cha nit di

dng cc loi phn bn hu c v v c.

Bi tp

1. Vit cng thc electron v cng thc cu to ca axit nitric v cho bit nguyn t nitc s oxi ho l bao nhiu.

2. Lp phng trnh ho hc ca cc phn ng sau y :

a) Fe + HNO3(c,nng) NO2 + ... c) Ag + HNO3(c) NO2 + ...

b) Fe + HNO3(long) NO + ... d) P + HNO3(c) NO2 + H3PO4 + ...

3. S phn ng sau y cho thy r vai tr ca thin nhin v con ngi trong vicchuyn nit t kh quyn vo trong t, cung cp ngun phn m cho cy ci :

+

X NO X+ NO2++

2X H O

y Z+ Ca(NO3)2N2

+2H

M X+ NO X+ NO2+ +

2X H O

y M+ NH4NO3Hy vit phng trnh ho hc ca cc phn ng trong s chuyn ho trn.

4. Hp cht no sau y ca nit khng c to ra khi cho HNO3 tc dng vi kim loi ?

A. NO B. NH4NO3 C. NO2 D. N2O5Hy chn p n ng.

5. Ti sao khi iu ch axit nitric bc khi phi s dng H2SO4 c v NaNO3 dng rn ?

6. Phn ng gia HNO3 vi FeO to ra kh NO. Tng cc h s trong phng trnh caphn ng oxi ho kh ny bng :

A. 22 B. 20 C. 16 D. 12

Hy chn p n ng.

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7. Cho 13,5 gam nhm tc dng va vi 2,2 lt dung dch HNO3

, phn ng to ra

mui nhm v mt hn hp kh gm NO v N2O. Tnh nng mol ca dung dch

HNO3. Bit rng t khi ca hn hp kh i vi hiro bng 19,2.

8.* t chy hon ton 4,4 g mt sunfua kim loi c cng thc MS (kim loi M c ccs oxi ho +2 v +3 trong cc hp cht) trong lng d oxi. Cht rn thu c sau

phn ng c ho tan trong mt lng va dung dch HNO3 37,8%. Nng

phn trm ca mui trong dung dch thu c l 41,7%.

a) Xc nh cng thc ca sunfua kim loi.

b) Tnh khi lng dung dch HNO3 dng.

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Phn ng vi mui : Al

3+

+ 3NH3 + 3H2O

Al(OH)3

+ 43NH

+

Kh nng to phc cht tan: Cu(OH)2 + 4NH3 [Cu(NH3)4](OH)2

Tnh kh: + 3CuO + 3Cu + 3H32NHot

2N 2O

b) Mui amoni

D tan trong nc, l cht in li mnh.

Trong dung dch, ion l axit :4NH+

4NH+ + H2O NH3+H3O

+

Tc dng vi kim to ra kh amoniac.

D b nhit phn hu.

c) Axit nitric

L axit mnh.

L cht oxi ho mnh.

HNO3oxi ho c hu ht cc kim loi. Sn phm ca phn ng c th l

, tu thuc nng ca axit v tnh kh mnh

hay yu ca kim loi.

4 2 1 0 3

22 2N O , N O, N O, N , NH NO+ + +

4 3

HNO3 c oxi ho c nhiu phi kim v cc hp cht c tnh kh.

d) Mui nitrat

D tan trong nc, l cht in li mnh.

D b nhit phn hu.

Nhn bit ion bng phn ng vi Cu kim loi v H3NO

2SO4.

Bi tp1. Vit cc phng trnh ho hc thc hin cc dy chuyn ho sau :

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a) NH3 oCuO

t

+

(kh)A 2

o

H

t , p, xt

+

NH32

o

O

t , Pt

+

C2O+

D 2 2O , H O+ +

E NaOH+ Got

(rn)H

b) NO2(5) NO NH

(4) 3 N

(2)

(3) 2 NO

(1)

(6) (7)

HNO3 Cu(NO(8) 3)2 CuO Cu

(9)

(10)

2. Cht kh A c mi xc, phn ng vi kh clo theo cc cch khc nhau sauy, tu theo iu kin phn ng.

a) Trong trng hp dkh A th xy ra phn ng : 8A + 3Cl2cht rn kh cht kh

6C D+

b) Trong trng hp dkh clo th xy ra phn ng : 2A + 3Cl2 D +cht kh

6E

Cht rn C mu trng, khi t nng b phn hu thun nghch, bin thnh cht

A v cht E. Khi lng ring ca kh D l 1,25 g/l (ktc).

Hy xc nh cc cht A, C, D, E v vit phng trnh ho hc ca cc phn ng.

3. Hy chn p n ng trong cc trng hp sau :

a) Phn ng gia kim loi magie vi axit nitric c gi thit ch to ra init

oxit. Tng cc h s trong phng trnh ho hc bng

A. 10 ; B. 18 ; C. 24 ; D. 20

b) Phn ng gia kim loi Cu vi axit nitric long gi thit ch to nit

monooxit. Tng cc h s trong phng trnh ho hc bng

A. 10 ; B. 18 ; C. 24 ; D. 20

4. Bng phng php ho hc, hy nhn bit cc dung dch sau : NH3,

(NH4)2SO4, NH4Cl, Na2SO4. Vit cc phng trnh ho hc.

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PhotphoBi 14(1 tit)

Bit cu to phn t, cc dng th hnh v hiu tnh cht ho

hc ca photpho.

Bit mt s dng tn ti ca photpho trong t nhin, phng

php iu ch v ng dng ca photpho trong i sng v snxut.

I Tnh cht vt l

n cht photpho c th tn ti mt s dng th hnh, trong quan trngnht l photpho trng v photpho .

1. Photpho trng

Photpho trng l cht rn khng mu hoc vngnht, trng ging nh sp, c cu trc mng tinh thphn t : cc nt mng l cc phn t hnh t din

P4 (hnh 2.11). Cc phn t P4 lin kt vi nhau bnglc tng tc yu. Do , photpho trng mm, d

nng chy (tnc = 44,1oC).

Photpho trng khng tan trong nc, nhng tannhiu trong cc dung mi hu c nh benzen, cacbonisunfua, ete,... , rt c, gy bng nng khi ri vo da.

Hnh 2.11. Cu trc ca phn tphotpho

Photpho trng bc chy trong khng kh nhit trn 40 oC, nn c boqun bng cch ngm trong nc. nhit thng, photpho trng pht quangmu lc nht trong bng ti. Khi un nng n nhit 250oC khng c khngkh, photpho trng chuyn dn thnh photpho l dng bn hn.

2. Photpho

Photpho l cht bt mu c cu trc polime (hnh 2.12) nn kh nngchy v kh bay hi hn photpho trng.

Photpho khng tan trong cc dung mi thng thng, d ht m v chyra, bn trong khng kh nhit thng v khng pht quang trong bng ti.

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Hnh 2.12.Cu trc polime ca photpho

N ch bc chy nhit trn 250

o

C. Khi un nng khng c khng kh,photpho chuyn thnh hi, khi lm lnh th hi ca n ngng t li thnhphotpho trng. Trong phng th nghim, ngi ta thng s dng photpho .

II Tnh cht ho hc

Do lin kt trong phn t photpho km bn hn trong phn t nit nn iu

kin thng photpho hot ng ho hc mnh hn nit, mc d m in ca

photpho (2,19) nh hn ca nit (3,04).

Trong hai dng th hnh, photpho trng hot ng hn photpho . n

gin, trong cc phn ng ho hc ngi ta vit phn t photpho di dng mt

nguyn t P. Khi tham gia phn ng ho hc, s oxi ho ca photpho c th tng

t 0 n +3 hoc +5, c th gim t 0 n 3, nn photpho c th th hin tnh kh

vtnh oxi ho.

1. Tnh oxi ho

Photpho ch th hin r rt tnh oxi ho khi tc dng vi mt s kim loi hot

ng, to ra photphua kim loi.

Th d : + 3Ca

0

2Po

t

3

23Ca P

canxi photphua

2. Tnh kh

Photpho th hin tnh kh khi tc dng vi cc phi kim hot ng nh oxi,

halogen, lu hunh,... cng nhvi cc cht oxi ho mnh khc.

a)Tc dng vi oxi

Khi t nng, photpho chy trong khng kh to ra cc oxit ca photpho :

Thiu oxi : + 3O

0

4P 2

3

2 32 P O+

iphotpho trioxit

Doxi : + 5O0

4P 25

2 52 P O+

iphotpho pentaoxit

b)Tc dng vi clo

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Khi cho clo i qua photpho nng chy, s thu c cc hp cht photpho clorua

Thiu clo : + 3Cl0

2P 23

32 P C l+

photpho triclorua

Dclo : + 5Cl0

2P 25

52 P C l+

photpho pentacloruac)Tc dng vi cc hp cht

Photpho tc dng d dng vi cc hp cht c tnh oxi ho mnh nhHNO3 c,

KClO3, KNO3, K2Cr2O7,...

Th d : 6P + 5KClO3 3P2O5 + 5KCl

III ng dng

Phn ln photpho sn xut ra c dng sn xut axit photphoric, phn cnli ch yu dng trong sn xut dim. Thuc gn u que dim (cn gi l thuc

u dim) gm cht oxi ho mnh (nhKClO3,...), cht kh (nh lu hunh,...) vkeo dnh. Thuc qut v bao dim l bt photpho v keo dnh. tng cst, ngi ta trn bt thu tinh nghin mn vo c hai th thuc trn. Khi qut quedim vo v bao dim, nhng ht nh photpho tc dng vi cht oxi ha mnhlin bc chy, lm chy thuc u dim, ri que dim bc chy theo.

Ngoi ra, photpho cn c dng vo mc ch qun s : sn xut bom, n

chy, n khi,...

IV Trng thi t nhin. iu ch

1. Trong t nhin khng gp photpho trng thi t do v n kh hot ng vmt ho hc. Phn ln photpho trong v Tri t nm dng mui ca axit

photphoric. Hai khong vt chnh ca photpho l apatit 3Ca3(PO4)2.CaF2 v

photphoritCa3(PO4)2 (hnh 2.13).

61

Hnh 2.13. Mt s khong vt ca photphoa) apatit ; b) photphorit

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Axit photphoricv mui photphat

Bit cu to phn t, tnh cht vt l, ho hc ca axit

photphoric v tnh cht ca cc mui photphat.

Bit nhng ng dng v phng php iu ch axit photphoric.

I Axit photphoric

1. Cu to phn t

Phn t H3PO4 c cu to :H OH O P OH O

=

Cng thc cu to ca H3PO4 cn c th biu din nhsau(1) :

H OH O P OH O

Bi 15(2 tit)

Trong hp cht H3PO4, photpho c s oxi ho cao nht l +5.

2. Tnh cht vt lAxit photphoric, cn gi l axit orthophotphoric (H3PO4) l cht tinh th,

trong sut, khng mu, nng chy 42,5oC, rt ho nc nn d chy ra, tan

trong nc theo bt k t l no. Axit photphoric thng dng l dung dch c,snh, c nng 85%.

3. Tnh cht ho hc

a)Tnh oxi ho kh : Khc vi nit, photpho mc oxi ho +5 bn hn.Do vy, axit photphoric kh b kh, khng c tnh oxi ho nhaxit nitric.

b) Tc dng bi nhit : Khi un nng n khong 200 250oC, axit

photphoric mt bt nc, bin thnh axit iphotphoric H4P2O7 :

2H3PO4 H4P2O7 + H2O

(1) Cch vit ny ph hp vi quy tc bt t.

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Tip tc un nng n khong 400

500

o

C, axit iphotphoric li mt bt n

c,bin thnh axit metaphotphoric :

H4P2O7 2HPO3 + H2O

Cc axit HPO3, H4P2O7 li c th kt hp vi nc to ra axit H3PO4.

c)Tnh axit

Axit H3PO4 l axit ba ln axit, c mnh trung bnh. Trong dung dch nphn li theo ba nc. Di y l hng s phn li axit 250C.

Nc 1 : H3PO4 H+

+ 2 4H PO ; K1 = 7,6.10

3

Nc 2 : 2 4H PO H

++ 24HPO ; K2 = 6,2.10

8

Nc 3 : 24HPO H

++ 34PO

; K3 = 4,4.1013

S phn li ch yu xy ra theo nc 1, nc 2 yu hn v nc 3 rt yu. Nh vy,

trong dung dch axit photphoric ngoi cc phn t H3PO4 khng phn li, cn c cc

ion H+, ihirophotphat 2 4H PO , hirophotphat 24HPO

v photphat , khng

k H

34PO

+ v OH do nc phn li ra.

Dung dch H3PO4 c nhng tnh cht chung ca axit, nh lm i mu qutm thnh , tc dng vi oxit baz, baz, mui, kim loi,...

Khi tc dng vi oxit baz hoc baz, tu theo lng cht tc dng m axit

photphoric to ra mui trung ho, mui axit hoc hn hp mui :Th d : H3PO4 + NaOH NaH2PO4 + H2O

H3PO4 + 2NaOH Na2HPO4 + 2H2O

H3PO4 + 3NaOH Na3PO4 + 3H2O

4. iu ch v ng dng

a) Trong phng th nghim, axit photphoric c iu ch bng cch dng

HNO3 c oxi ho photpho :

P + 5HNO3 + 5NO

3H PO

4 2+ H

2O

b) Trong cng nghip :

Cho H2SO4 c tc dng vi qung photphorit hoc qung apatit :

Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4

Tch mui CaSO4ra v c c dung dch, ri lm lnh axit kt tinh. Axitphotphoric iu ch bng phng php ny khng tinh khit, c cht lng thp.

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iu ch H3PO4 c tinh khit v

nng cao hn, ng

i ta t chyphotpho c P2O5, ri cho P2O5 tc dng vi nc.

4P + 5O2ot 2P2O5 ; P2O5 + 3H2O 2H3PO4.

Mt lng ln axit photphoric sn xut ra c dng iu ch cc muiphotphat v sn xut phn ln.

II Mui photphat

Mui photphat l mui ca axit photphoric. Axit photphoric to ra ba loi mui :

mui photphat trung ho v hai mui photphat axit.Th d : Mui photphat trung ho : Na3PO4, Ca3(PO4)2, (NH4)3PO4

Mui ihirophotphat : NaH2PO4, Ca(H2PO4)2, NH4H2PO4

Mui hirophotphat : Na2HPO4, CaHPO4, (NH4)2HPO4

1. Tnh cht ca mui photphat

a) Tnh tan :

Tt c cc mui ihirophotphat u tan trong nc.

Trong s cc mui hirophotphat v photphat trung ho ch c mui natri, kali,amoni l d tan, cn mui ca cc kim loi khc u khng tan hoc t tan trong nc.

b) Phn ng thu phn : Cc mui photphat tan b thu phn trong dung dch.

Th d : Na3PO4 + H2O Na2HPO4 + NaOH

+ H34PO

2O 24HPO

+ OH

Do , dung dch Na3PO4 c mi trng kim, lm qu tm ng mu xanh.

2. Nhn bit ion photphat

Thuc th nhn bit ion 34PO trong dung dch mui photphat l bc nitrat.

Th nghim: Nh vo ng nghim 5-6 git dung dch Na3PO4ri thmvo 3-4 git dung dch AgNO3.Khi s to thnh kt ta mu vng, tan c trongdung dch axit nitric long. Phng trnh ion rt gn :

3Ag+ + Ag34PO

3PO4 (mu vng)

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B

i tp1. Vit cng thc cu to ca axit iphotphoric, axit metaphotphoric v cho bit trong cc

axit ny s oxi ho ca photpho l bao nhiu.

2. Vit cc phng trnh phn ng thc hin dy chuyn ho sau y :

Qung photphorit photpho iphotpho pentaoxit axit photphoric amoni

photphat axit photphoric canxi photphat.

3. in cht thch hp vo ch c du ? trong cc s sau :

a) + ? + ? b)2 4H PO 2

4HPO 2

4HPO + ? + ?2 4H PO

4. Bng phng php ho hc, hy phn bit dung dch HNO3 v dung dch H3PO4.

5. Axit A l cht rn, trong sut, khng mu, d tan trong nc. Khi thm canxi oxit vodung dch A th to thnh hp cht B mu trng, khng tan trong nc. Khi nung B nhit cao vi ct v than th to thnh n cht photpho c trong thnh phn ca A.Cho bit A, B, l nhng cht g ? Vit phng trnh ho hc ca cc phn ng.

6. Thm 0,15 mol KOH vo dung dch cha 0,1 mol H3PO4. Sau phn ng, trong dungdch c cc mui :

A.KH2PO4 vK2HPO4 B. KH2PO4 vK3PO4C. K2HPO4vK3PO4 D.KH2PO4 ,K2HPO4 vK3PO4

Hy chn p n ng.

7.Thm 6 g P

2O

5vo 25 ml dung dch H

3PO

46% (D = 1,03 g/ml). Tnh nng phn

trm ca H3PO4 trong dung dch thu c.

8. Rt dung dch cha 11,76 g H3PO4 vo dung dch cha 16,8 g KOH. Tnh khi lngca tng mui thu c sau khi cho dung dch bay hi n kh.

tliu Vai tr sinh hc ca photpho

Photpho rt cn cho ngi v ng vt. Trong c th ngi, khong 90%photpho tp trung xng, khong 10% tp trung cc c, gn 1% cc t bo

no (di dng cc hp cht v c vhu c).

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Phn bn ho hcBi 16(1 tit)

Bit cc nguyn t dinh dng no cn thit cho cy trng.

Bit c thnh phn ho hc ca cc loi phn m, phnln, phn kali, phn phc hp,... v cch iu ch cc loi phnbnny.

Phn bn ho hc l nhng ho cht c cha cc nguyn t dinh dng, c

bn cho cy nhm nng cao nng sut cy trng.Cy ng ho c C, O, H t khng kh v nc, cn i vi cc nguyn t

khc th cy hp th t t. t trng trt b ngho dn cc nguyn t dinh d ng,v vy cn bn phn b sung cho t nhng nguyn t .

C ba loi phn bn ho hc chnh lphn m, phn ln vphn kali.

I Phn m

Phn m cung cp nit ho hp cho cy di dng ion nitrat v ion

amoni . Phn m c tc dng kch thch qu trnh sinh tr

ng ca cy, l

mtng t l ca protein thc vt. C phn m, cy trng s pht trin nhanh, chonhiu ht, c hoc qu. Cc loi phn m chnh l phn m amoni, phn mnitrat, phn m ur.

3NO

4NH

+

dinh dng ca phn m c nh gi bng hm lng % N trong phn.

1. Phn m amoni

l cc mui amoni NH4Cl, (NH4)2SO4, NH4NO3,... Cc mui ny c

iu ch khi cho amoniac tc dng vi axit tng ng. Th d :

2NH3 + H2SO4 (NH4)2SO4.

Khi tan trong nc, mui amoni b thu phn to ra mi trng axit, nn chthch hp khi bn phn ny cho cc loi t t chua, hoc t c kh chuatrc bng vi (CaO).

2. Phn m nitrat

l cc mui nitrat NaNO3, Ca(NO3)2,... Cc mui ny c iu ch khi

cho axit nitric tc dng vi mui cacbonat ca cc kim loi tng ng.

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Th d : CaCO3 + 2HNO3

Ca(NO3)2 + CO2 + H2OPhn m amoni v phn m nitrat khi bo qun thng d ht nc trongkhng kh v chy ra. Chng tan nhiu trong nc, nn c tc dng nhanh i vicy trng, nhng cng d b nc ma ra tri.

3. Ur

Hnh 2.15. Ur

Ur [(NH2)2CO] l cht rn mu trng (hnh2.15), tan tt trong nc, cha khong 46% N, c

iu ch bng cch cho amoniac tc dng vi CO2

nhit 180 200oC, di p sut ~ 200 atm :

CO2 + 2NH3 (NH2)2CO + H2O.Trong t, di tc dng ca cc vi sinh vt ur b

phn hu cho thot ra amoniac, hoc chuyn dnthnh mui amoni cacbonat khi tc dng vi nc :

(NH2)2CO + 2H2O (NH4)2CO3 nc ta c nh my phn m Bc Giang sn xut ur dng ht, nh my

phn m Ph M sn xut ur t kh m du.

II Phn ln

Phn ln cung cp photpho cho cy di dng ion photphat. Phn ln cn thitcho cy thi k sinh trng do thc y cc qu trnh sinh ho, trao i cht vnng lng ca thc vt. Phn ln c tc dng lm cho cnh l kho, ht chc, qu

hoc c to. dinh dng ca phn ln c nh gi bng hm lng % P2O5tng ng vi lng photpho c trong thnh phn ca n.

Nguyn liu sn xut phn ln l qung photphorit v apatit. Mt s loiphn ln chnh l supephotphat, phn ln nung chy,...

1. Supephotphat

C hai loi supephotphat lsupephotphat n vsupephotphat kp. Thnh phn

chnh ca c hai loi l

mui tan canxi ihirophotphat.a) Supephotphat n cha 14 20% P2O5, c sn xut bng cch cho bt

qung photphorit hoc apatit tc dng vi axit sunfuric c :

Ca3(PO4)2 + 2H2SO4 Ca(H2PO4)2 + 2CaSO4

Cy trng ng ho d dng mui Ca(H2PO4)2, cn CaSO4 l phn khng c

ch, lm rn t.

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n

c ta, Cng ti supephotphat v

ho cht Lm Thao

Ph Th sn xut loisupephotphat n ny t qung apatit Lo Cai.

b)Supephotphat kp cha hm lng P2O5 cao hn (40 50% P2O5) v ch c

Ca(H2PO4)2. Qu trnh sn xut supephotphat kp xy ra qua hai giai on : iuch axit photphoric, v cho axit phophoric tc dng vi photphorit hoc apatit :

Ca3(PO4)2 + 3H2SO4 2H3PO4 + 3CaSO4

Ca3(PO4)2 + 4H3PO4 3Ca(H2PO4)2

2. Phn ln nung chy

sn xut phn ln nung chy, ngi ta nung hn hp bt qung apatit (hayphotphorit) vi x vn (thnh phn chnh l magie silicat) v than cc nhit

trn 1000oC trong l ng. Sn phm nng chy t l i ra c lm ngui

nhanh bng nc khi cht b v thnh cc ht vn, sau sy kh v nghinthnh bt.

Thnh phn chnh ca phn ln nung chy l hn hp photphat v silicat ca

canxi v magie (cha 12 14% P2O5). Cc mui ny khng tan trong nc, nn

cng ch thch hp cho loi t chua.

n

c ta, phn ln nung chy

c sn xut Vn in (H

Ni) v

mt sa phng khc.

III Phn kali

Phn kali cung cp cho cy trng nguyn t kali di dng ion K+

. Phn kaligip cho cy hp th c nhiu m hn, cn cho vic to ra cht ng, chtbt, cht x v cht du, tng cng sc chng bnh, chng rt v chu hn ca

cy. dinh dng ca phn kali c nh gi bng hm lng % K2O tngng vi lng kali c trong thnh phn ca n.

Hai mui kali clorua v kali sunfat c s dng nhiu nht lm phn kali.

Tro thc vt cng l mt loi phn kali v c cha K2CO3.

IV mt s loi Phn bn khc

1. Phn hn hp v phn phc hp

Phn hn hp v phn phc hp l loi phn bn cha ng thi hai hoc banguyn t dinh dng c bn.

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Phn hn hp cha c ba nguyn t N, P, K c gi lphn NPK. Loi

phn ny l sn phm khi trn ln cc loi phn n theo t l N : P : K khc

nhau tu theo loi t v cy trng. Th d : Nitrophotka l hn hp ca

(NH4)2HPO4 v KNO3.

Phn phc hp c sn xut bng tng tc ho hc ca cc cht. Th d :

Amophot l hn hp cc mui NH4H2PO4 v (NH4)2HPO4 thu c khi cho

amoniac tc dng vi axit photphoric.

2. Phn vi lng

Phn vi lng cung cp cho cy cc nguyn t nh bo (B), km (Zn), mangan(Mn), ng (Cu), molipen (Mo),... dng hp cht. Cy trng ch cn mt lng

rt nh loi phn bn ny tng kh nng kch thch qu trnh sinh trng v trao

i cht, tng hiu lc quang hp,... Phn vi lng c a vo t cng vi phn

bn v c hoc phn bn hu c v ch c hiu qu cho tng loi cy v tng loi

t, dng qu lng quy nh s c hi cho cy.

Bi tp1. Cho cc mu phn m sau y : amoni sunfat, amoni clorua, natri nitrat. Hy dng

cc thuc th thch hp nhn bit chng. Vit phng trnh ho hc ca cc phnng dng.

2. Mt trong nhng phng php iu ch canxi nitrat l cho vi hoc phn tcdng vi axit nitric long. Cn amoni nitrat c th c iu ch bng cch cho canxinitrat tc dng vi amoni cacbonat. Vit cc phng trnh ho hc v cho bit ti saocc phn ng ny xy ra hon ton.

3. T khng kh, than, nc v cc cht xc tc cn thit, hy lp s iu ch

phn m NH4NO3.

4. Ti sao khng c trn supephotphat vi vi ? Gii thch v vit phng trnh ho hcca phn ng.

5. Supephotphat n c iu ch t mt loi bt qung c cha 73% Ca 3(PO4)2, 26%

CaCO3 v 1% SiO2.

a) Tnh khi lng dung dch H2SO4 65% tc dng vi 100 kg bt qung .

b) Supephotphat n thu c gm nhng cht no ? Tnh t l % P2O5 trong loisupephotphat n trn.

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Luyn tp

Tnh cht ca photpho

v cc hp cht ca photpho

Bi 17(1 tit)

Bit tnh cht ca cc dng th hnh ca photpho, ca axitphotphoric v mui photphat.Bit nhng ng dng, phng php iu ch photpho v cchp cht ca photpho.

Rn luyn k nng gii bi tp.

I Kin thc cn nm vng

1. n cht photpho

Nguyn t khi : 31 m in : 2,19

Cu hnh electron ca nguyn t : 1s22s22p63s23p3P

Cc s oxi ho : 3, 0, +3, +5.

P trng :

Mng tinh th phn t, mm, dnng chy, c, pht quang trong bngti, chuyn dn thnh P , khng tantrong nc, d tan trong mt s dungmi hu c.

P :

C cu trc polime, bn, khng tan

trong cc dung mi. Chuyn thnh hi

khi un nng khng c khng kh v

ngng t hi thnh photpho trng.

2o

5O

2 5t

P O+

+

2o

5Cl

5t

PCl+

+

o3Ca

3 2t

Ca P

+ : photpho th hin tnh oxi ho

photpho th hin tnh kh0P

2. Axit photphoric

L axit ba nc, c mnh trung bnh. Khng c tnh oxi ho.

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o o

2 2

t t

3 4 4 2 7H O H OH PO H P O HPO+ + 3

To ra ba loi mui photphat khi tc dng vi dung dch kim.

3. Mui photphat

Photphat trung ho (Na3PO4, Ca3(PO4)2,...), ihirophotphat (NaH2PO4,

Ca(H2PO4)2,...), hirophotphat (Na2HPO4, CaHPO4,...).

D tan trong nc : Tt c cc mui photphat ca natri, kali, amoni.

ihirophotphat ca cc kim loi khc.

Khng tan hoc t tan trong nc : hirophotphat v photphat trung ho cacc kim loi, tr ca natri, kali v amoni.

Nhn bit ion bng phn ng : 334PO 3

4Ag PO+ + 3 4

(vng)

Ag PO

II Bi tp

1. Nu nhng im khc bit trong cu to nguyn t gia nit v photpho.

2. Lp cc phng trnh ho hc dng phn t v dng ion rt gn ca cc

phn ng xy ra trong dung dch ca cc cht

a) kali photphat v bari nitrat. b) natri photphat v nhm sunfat.

c) kali photphat v canxi clorua. d) natri hirophotphat v natri hiroxit.

e) canxi ihirophotphat (1 mol) v canxi hiroxit (1 mol).

g) canxi ihirophotphat (1 mol) v canxi hiroxit (2 mol).

3. Chn cng thc ng ca apatit :

A. Ca3(PO4) 2 ; B. Ca(PO3)2 ; C. 3Ca3(PO4) 2.CaF2 ; D. CaP2O7

4. Cho 44g NaOH vo dung dch cha 39,2 g H3PO4. Sau khi phn ng xy ra

hon ton, em c dung dch thu c n cn kh. Hi nhng mui no c tonn v khi lng mui khan thu c l bao nhiu ?

A. Na3PO4 v 50 g ; C. NaH2PO4 v 49,2 g ; Na2HPO4 v 14,2 g ;

B. Na2HPO4 v 15 g ; D. Na2HPO4 v 14,2 g ; Na3PO4 v 49,2 g.

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Hy tm p n ng

5. Thm 10 g dung dch bo ho bari hiroxit ( tan l 3,89 g trong 100 g

nc) vo 0,5 ml dung dch axit photphoric nng 6 mol/l. Tnh lng cc hpcht ca bari c to thnh.

thc hnh

Tnh cht ca mt s hp cht

nit, photpho

Bi 18(1 tit)

I Mc tiu

Bit thao tc th nghim an ton, chnh xc.

Th nghim chng minh : Tnh tan nhiu ca amoniac

Tnh cht oxi ho mnh ca axit nitric

Phn bit cc loi phn bn ho hc.

II Ni dung th nghim v cch tin hnh

Th nghim 1. iu ch kh amoniac v th tnh cht ca dung dch amoniac

a) iu ch kh amoniac (hnh 2.16)

Hnh 2.16. iu ch kh amoniac

Trn khong 45 g NH4Cl vi

56 g NaOH ri cho vo ng nghimkh (1). Dng nt c lp ng dn kh(2) nt ming ng nghim. unng nghim bng n cn v thu khamoniac thot ra bng ng nghim

kh (3). Khi y kh amoniac thcho nhanh khong 1ml nc vo vnt cht ming ng nghim (3) bngnt cao su. Lc mnh cho khamoniac tan ht trong nc.

b) Th tnh cht ca dung dch amoniac

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Chia dung dch amoniac thu c trn vo hai ng nghim nh. Cho vi git

dung dch phenolphtalein vo ng th nht v 5-6 git dung dch mui nhm

clorua vo ng th hai. Nhn xt s xut hin mu ca dung dch ng nghim

th nht v cho bit dung dch amoniac c mi trng g ? ng nghim th haixy ra hin tng g ? Vit phng trnh ho hc ca phn ng.

Th nghim 2.Tnh oxi ho ca axit nitric

1. Ly vo ng nghim 0,5 ml dung dch HNO3 c, ri cho mt mnh nh

ng kim loi vo. Quan st mu ca kh bay ra v mu ca dung dch thu c.

Gii thch v vit phng trnh ho hc.

2. Cng lm nh th nghim trn, nhng thay bng 0,5 ml dung dch HNO3

long (nng gn 2 mol/l). un nh ng nghim trn n cn. Quan st mu ca

kh bay ra v mu ca dung dch. Gii thch, vit phng trnh ho hc.

Th nghim 3.Phn bit mt s loi phn bn ho hc

Cho cc mu phn bn ho hc sau y : amoni sunfat, kali clorua v

supephotphat kp. Ly mi loi mt t (c bng ht ng) vo tng ng nghim

ring. Cho vo mi ng nghim 4 5 ml nc ct v lc nh ng nghim cho n

khi cc cht tan ht.

a) Phn m amoni sunfat

Ly dung dch phn m amoni sunfat va

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